On this page you can find out about PhD opportunities currently available in Physics and Astronomy. Click on a research area or a project title below to find out more.
Some of these projects come with specific funding (eg, from a research council or Centre for Doctoral Training) to cover your tuition fees and living expenses. If you successfully apply for one of these projects, and you meet the eligibility requirements, you will be automatically awarded the funding. These projects are marked 'FUNDED' in the list below.
If a project does not come with specific funding, that does not mean that there is no funding available. You may be awarded a scholarship after you have submitted your application – let us know if you wish to be considered for a scholarship by including this in your application form. We also accept applications from students who are applying for funding separately, or have funding in place already.
You can find out about scholarships on the following webpage:
If you would like any more information or have any questions, please contact us.
Do you have your own idea for a project?
Find a potential supervisor by visiting our research webpages. Contact a member of academic staff to find out about PhD opportunities in their area.
Centres for Doctoral Training
Other funded PhD opportunities are available through the Centres for Doctoral Training or Doctoral Training Partnerships that our staff contribute to.
Visit the webpages for these centres to find out more about their projects:
Once you have identified a potential project and supervisor, please complete the University's postgraduate online application form to apply. If you wish to be considered for a scholarship, you should state this in the form. You should also include any information you have about funding that you are applying for separately, or that you have in place already. It is a good idea to contact the supervisor of any PhD opportunity you want to apply for, before you submit your application.
We usually ask for an upper second class (2:1) honours BSc or MSc degree in physics or engineering.
Our decision on whether to offer you a place will also be based on the research proposal or personal statement you submit, your CV and references, and any interviews you complete. Students will also need to meet our English language requirements, and international students will need to get clearance through the Academic Technology Approval Scheme (ATAS). Find out more about English language requirements and ATAS on our webpage for international students:
Astronomy and astrophysics
|High-speed astrophysics with HiPERCAM, ULTRACAM and ULTRASPEC||
HiPERCAM, ULTRACAM and ULTRASPEC are high-speed cameras built by Sheffield/Warwick/UKATC for the study of astrophysics on fast timescales. Extreme astrophysical conditions can be found in our Galactic neighbourhood by studying the compact remnants of stars: white dwarfs, neutron stars and black holes. The dynamical timescales of these compact objects range from seconds to milliseconds, which means that much of the variability observed from them occurs on such fast timescales. Existing common-user instrumentation on the world's major telescopes is unable to obtain high time-resolution data, which is why we have developed HiPERCAM, ULTRACAM and ULTRASPEC. The aim of this PhD project will be to exploit these unique instruments on the 10.4m GTC, 4.2m WHT, 3.5m NTT and 2.4m TNT to study physics in extreme conditions, such as accretion onto black holes, the structure of white dwarfs, the evolution of close binary stars, and the physics of pulsars.
|Masses of White Dwarfs in Interacting Binary Stars||
Type IA supernovae are the key to our understanding of the expansion of the Universe. Surprisingly, then, we still do not fully understand their origin. It is widely recognised that type IA supernovae come from white dwarfs being driven above the Chandrasekhar mass, but there is no consensus on how this happens. Candidate progenitors include the merger of two, lower mass, white dwarfs, or white dwarfs accreting rapidly from sub-giant stars. Neither of these two models can explain all the observations. One channel that has often been ignored is a white dwarf accreting from a low-mass star. These objects, known as catalcysmic variables (CVs), are thought not to be IA progenitors as the mass accreted by the white dwarf is expected to be expelled in Nova eruptions. However, the masses of white dwarfs in CVs is larger than isolated white dwarfs, suggesting that perhaps the white dwarfs in CVs can grow in mass after all. In this PhD, you will use light curve modelling to measure the white dwarf masses in a large sample of CVs to test the idea that CVs may, after all, be IA progenitors.
|The environments of star and planet formation||
Young stars are often found in high-density environments, this means that encounters between young stars can be common and this will change their binary properties and affect planet-forming discs. A PhD would involve investigating various computational and statistical aspects of young stars and their environments. These include dynamical and hydrodynamical simulations of stellar dynamics, statistical measures of complex distributions, examining and interpreting both observational, simulated and 'fake' data.
|Properties of evolved, hot luminous stars from large spectroscopic surveys||
Historically, spectroscopic studies of hot massive stars in the Milky Way and nearby galaxies have been restricted to small sample sizes. The advent of wide field, highly multiplexing spectroscopic instruments (WHT/WEAVE, VISTA/4MOST) permit thousands of massive stars to be studied, whilst the upcoming GAIA DR2 release provide reliable parallaxes for stars at distances of several kpc. This project will combine the WEAVE Galactic Plane Survey and GAIA parallaxes to investigate the properties of a large sample of post-main sequence hot, luminous stars (blue supergiants, Wolf-Rayet stars) for the very first time, confronting predictions from evolutionary models, leading to their refinement.
|How do supernovae explode?||
Supernovae are some of the most important objects in the Universe. They are responsible for sculpting the shapes of galaxies, releasing heavy chemical elements into the Universe and can serve as cosmological lighthouses for measuring distances. Despite their utility, the exact nature of the explosion behind these events is one of the biggest unknowns in modern astronomy and holds the key to understanding some of the most extreme physical environments found in the Universe. This project is concerned with measuring the shapes of distant supernovae, despite them being too far away for us to see their shapes through direct imaging. The amount of polarization measured for these events allows us to conduct 3D tomography to reconstruct their shapes and identify the physics of the explosion mechanism. This project is primarily computational, building radiative transfer models to study how light generated in the explosion escapes from the ejecta and how the shape of the ejecta is imprinted on the polarization.
|How do people first learn to spot patterns?||
How people separate things into objects that look the same and objects that look different? How do people identify which particular characteristics are important for discriminating between different types of objects? In this project we will consider machine learning and its application to the observations of transients, that are now being produced by the first generation of survey telescopes and will become progressively important in the next decade with the advent of the Large Synoptic Survey Telescope (LSST) and the European-Extremely Large Telescope (E-ELT). At Sheffield, we have a head start in the field, being a partner in GOTO (Gravitational Wave Optical Transient Observatory), which will detect a large number of brand new types of transients. This project is primarily concerned with developing unsupervised learning algorithms to mimic the way in which humans learn when given a new set of information they’ve never seen before. In the case of supernovae, the classification scheme has been developed over the last 80 years, with new branches being proposed on a regular basis. This project aims to answer the question: what is the most natural way to differentiate and classify different types of transient?
This project also comes with the possibility to collaborate with computer scientists based both in Sheffield and Thailand.
|Where do supernovae explode?||
The deaths of massive stars are marked by dramatic explosions known as supernovae. These massive stars are also very young and can be found close to the place where they formed and in the vicinity of other massive stars (though slightly less massive than the one that exploded). A fundamental question in the field of supernova research is which types of star will explode as supernovae of a given type. This project aims to utilise observations of star forming regions in nearby galaxies made with the Hubble Space Telescope. Spanning from the ultraviolet to near infrared wavelengths, these images of individual stars provide a “fossil” record of the births and deaths of massive stars. Bayesian tools will be developed and applied to this data to understand the temporal and spatial distributions of the stars. Supernova-selected populations provide a unique window on massive star formation and evolution, that can also reveal the origin of the diversity of massive star supernovae and the physics of the explosion itself.
|What governs the growth of black holes||
Producing the definitive range of intrinsic AGN templates (lots of data reduction, moderate computation).
|How good is the far-IR as a tracer of star formation activity in AGN host galaxies?||
In order to understand the links between black hole growth and galaxy evolution it is crucial to have a "clean" indicator of the star formation activity in host galaxies of active galactic nuclei (AGN). The thermal far-infrared continuum emission has been proposed as such an indicator, however recent work by the Sheffield group has suggested that a substantial proportion of the far-IR continuum may radiated by kpc-scale dust that is heated by the AGN rather than by regions of star formation. This observational project will use deep observations taken with the HST, Spitzer, Herschel and ALMA telescopes to directly quantify the contribution of AGN heated dust at far-IR wavelengths, and hence assess whether the far-IR continuum is truly a good indicator of star formation activity in AGN host galaxies.
|How are AGN triggered?||
To accurately incorporate active galactic nuclei (AGN) into galaxy evolution models it is important to understand how and when AGN are triggered as their their host galaxies grow via gas accretion, and also whether the triggering mechanism depends on the luminosity of the AGN. This observational project will involve using deep imaging and spectroscopy observations of samples of nearby AGN to thoroughly investigate AGN triggering mechanisms.
|Quantifying star formation||
Stars form in relatively dense groups containing tens to millions of other stars, and these environments directly influence both young planets as they are forming, as well as the global evolution of galaxies. In order to understand the star formation process we need robust statistical methods to quantify the spatial and kinematic distributions of stars and gas in young star-forming regions. This PhD project will involve developing and extensively testing new statistical methods to quantify the distributions of stars and gas in both observed and simulated star-forming regions.
If you are applying for one of these projects, you may be able to apply for the a departmental scholarship or EPSRC studentship to cover your tuition fees and living expenses.
|Two-for-one photon conversion in synthetic proteins for energy harvesting||
Carotenoids are the most widespread of the natural pigments, important for photosynthesis, vision, human health and industry (market value $1.2bn). Surprisingly, carotenoids are also excellent candidates for singlet fission sensitizers, demonstrating strong absorption and fast (<100fs) singlet fission . However, problems remain: the mechanism of singlet fission and how to control it are not yet understood in carotenoids, and – crucially – it is not yet clear how to transfer the pairs of excited states into a photovoltaic for solar energy harvesting.
We hope to solve these problems using our brand-new synthetic carotenoid-bound-proteins, which demonstrate singlet fission, smooth film formation and increased pigment stability. You will explore the possibility of using our proteins to facilitate radiative transfer from the carotenoids to the solar cell, creating films that convert single high-energy photons into pairs of low-energy photons.
 Nature Reviews 2017, 2, 17063.  J. Am. Chem. Soc., 2015, 137, 5130.
We particularly encourage female applicants or applicants from under-represented groups. Any queries about part-time studies, parental leave or other issues can be addressed to our postgraduate administrator Laura Oliver email@example.com in confidence.
|Mechanisms of bacterial killing by the innate immune system||We live in constant contact with a plethora of microorganisms, many of which are capable of causing disease, but most of the time we remain healthy. This is largely due to the innate immune response which plays a key role in combating bacterial infection, yet it is relatively unexploited in medicine, partly because of lack of understanding of how it works. Recently we have developed new approaches using atomic force microscopy that have allowed us to image the bacterial cell wall with true molecular resolution for the first time, and are combining this with super-resolution optical imaging to provide new insights into how the wall is formed. This project, working from these advances, will take an interdisciplinary approach to find out how the human pathogen Staphylococcus aureus responds to contact with the human host, how it is impacted by action of innate antimicrobial agents, and ultimately the mechanism by which bacteria are killed. This will allow us to define those bacterial cell wall biophysical parameters that form the basis for the design and utilisation of new agents to sensitise target bacteria to the innate immune response, providing a route for bacterial treatment without antibiotics.
This project is based in the Department of Physics and Astronomy (with Prof Jamie Hobbs), working in collaboration with colleagues in Molecular Biology and Biotechnology (Prof Simon Foster) and Dr Helen Marriott (Dept Infection, Immunity and Cardiovascular Disease).
|Theoretical modelling of malaria invasion of red blood cells||
The malaria parasite invades red blood cells in the host and changes the shape and mechanics of these cells. The parasite reproduces inside the red blood cell until the host cell bursts releasing the parasites to infect more host cells. This aim of this theoretical project is to calculate how the malaria parasite enters the host cell and changes the shape and mechanics of these red blood cells. It is known that the parasite uses actin and myosin to push itself into the host cell. These are the same molecular ingredients used for classic cell motility but the structure of the actin and myosin machinery is known to be quite different. The details of how this machinery works are not yet well understood and theoretical modelling will help in this goal. Red blood cells have a characteristic biconcave disk (doughnut) shape. The inner surface of their membrane is covered with a network of a cytoskeleton protein called spectrin which in turn binds to the actin cytoskeleton. These cytoskeleton filaments maintain the red blood cell's shape and mechanical stability. We will theoretically model this cytoskeleton and calculate the forces involved when malaria parasite alters the red blood cell shape and mechanics. This project will be conducted in collaboration with partners in South Africa and therefore may involve travel there.
|A new mathematical framework for Aβ assembly in Alzheimer’s disease||
Amyloids are fibrous assemblies of misfolded protein which are responsible for a wide range of neurodegenerative diseases. While traditional models of nucleated polymerisation have been successfully applied to amyloid assembly under simplified experimental conditions, specific conditions in the human brain result in heterogeneous populations of immature assembly intermediates which add considerable complexity to the amyloid formation pathway. Although both atomistic and coarse-grained molecular dynamics simulations have provided crucial insights into the formation of these assemblies and their maturation into amyloid fibrils, computational limitations have prevented modelling of the entire amyloid assembly pathway. Moreover, although biochemical studies have provided evidence for positive feedback, by which mature fibrils facilitate the nucleation of additional amyloid fibrils and lead to spread of disease in the brain, the precise mechanistic details of this process have not been uncovered.
The deadline for this project is 24th January 2018.
|Cellular development and Chromatin Biology: A case study of non-equilibrium Statistical Physics||
Life for every organism starts as a single cell. With progressing time the cells first undergo division up to a point after which they undergo differentiation, i.e. different clusters of cells develop differently to form different parts of the organism. Several biological cues, at the level of gene expression, organization of the nuclear material, and tissue specific collective motion of cells dictate this process.
The aim of this project will be to theoretically develop a multiscale model of cellular development starting from gene-expression at the microscopic scale, chromatin organization in the nucleus at the mesoscale and morphological transitions at the tissue scale.
Analytical and numerical techniques rooted in nonlinear dynamics will be employed at the level of gene regulatory networks to predict cellular expression levels, theories of polymer dynamics (both simulations and analytical theory) will be used to model chromatin packing in the nucleus, while continuum mechanics (elasticity theory and fluid mechanics) augmented with biochemical reaction kinetics and physics of active matter will be used to understand tissue level morphological transitions that lead to developmental patterns.
A successful outcome of this project would be to understand how stem cells are intrinsically different from differentiated ones at the microscopic level and pave the way forward for a statistical understanding of stem cell biology, and chromosomal abnormalities.
|How do bacteria use ‘grappling hooks’ to move within biofilms?||Most bacteria live in surface-attached communities called biofilms. These structures protect cells from a wide variety of threats, including the antibiotics that doctors use to treat bacterial infections. While classically the cells within biofilms were considered to live sluggish, static lives, we now know that bacteria can use tiny ‘grappling hooks’ called pili to move within biofilms. Our group recently discovered that the movement of cells within biofilms is not random, but rather individuals can actively direct their movement to more favourable chemical environments (Oliveira, Foster & Durham, PNAS, 113, 2016). While this process, known as chemotaxis, has been intensively studied in free swimming bacteria, we know very little about the biological and physical mechanisms that bacteria use to navigate through biofilms.
This project will develop new experimental and theoretical approaches to resolve how bacteria generate pili-based chemotaxis within biofilms. We are especially interested in understanding mechanisms that underlie the highly coordinated, collective behaviour that is routinely observed when cells are densely packed together. Taken together, this project might lead to new ways to disrupt dangerous bacterial infections in patients or to rationally engineer biofilms in biotechnological applications.
This project will provide exposure to a wide variety of tools, including microfluidic experiments, sophisticated microscopic imaging, code/algorithm development, molecular biology, and mathematical modelling, however, the particulars of the project will be tailored to the student’s interests. Our current group is composed of biologists, mathematicians, physicists, and engineers – we welcome applications from potential students that are interested in highly interdisciplinary research. No prior experience with microbiology is required.
Contact: Dr William Durham (firstname.lastname@example.org)
|Understanding how magnetotactic bacteria respond to magnetic fields||
Some species of bacteria are magnetotactic, meaning that they have the unique capacity to sense and respond to magnetic fields. These bacteria possess magnetite nanoparticles called magnetosomes, which allow them to align with external magnetic fields like a compass needle. We can control the movement of these bacteria from afar by simply manipulating the magnetic fields that they experience. This capability has tremendous potential in biotechnological applications, for example, it may allow us to use cells as controllable drug delivery devices.
Our highly active group has more than 20 PhD students involved in research on a variety of topics in the area of semiconductor nanostructures. In 2018, we are seeking students for the following projects, with funding available for both UK and EU candidates. At any particular time there may also be associated postdoc positions.
|Semiconductor quantum optical circuits||
As a result of a five year large grant award (find out more) from the UK funding agency, EPSRC, several positions are available in highly topical areas of semiconductor physics and optics research. These include the physics of the first semiconductor quantum optical circuits, novel methods for spin readout and new types of single photon sources. All topics have the opportunity for advanced fabrication of nanoscale structures, and involve participation in research at the leading edge of semiconductor physics and photonics.
|Light-matter interaction in atomically thin two-dimensional materials beyond graphene||
The isolation of single-atomic layer graphene has led to a surge of interest in a large family of layered crystals with strong in-plane bonds and weak, van der Waals-like, interlayer coupling. Structures made by vertical stacking of different atomically thin 2D crystals provide a platform for creating new artificial materials with potential for discoveries and applications. In this PhD project you will work on exploring the potential of van der Waals nanolayer structures in photonics. We focus on studies of the light-matter interaction in 2D materials embedded in microcavities, opening new possibilities to explore and harness non-linear and quantum optics, and progress beyond the state-of-the-art in new materials physics and device applications. You will work closely with two expert supervisors Prof Alexander Tartakovskii and Dr Dmitry Krizhanovskii, whose groups have joined their effort and lead in the studies of light-matter interaction in 2D materials. Their research groups include 8 PhD students and 4 postdocs, with whom you will work as part of the joint team. You will perform advanced optics experiments in the state-of-the-art laboratories of the Sheffield group, work on novel device fabrication in the modern clean room and collaborate with leading groups around the world on 2D physics and technology. See further details at http://ldsd.group.shef.ac.uk/research/2d-materials/ and https://ldsd.group.shef.ac.uk/research/polaritons/
A fully funded PhD on this topic is available for UK students.
|Photonics and polaritonics with 2D materials beyond graphene||
The isolation of single-atomic layer graphene has led to a surge of interest in a large family of layered crystals with strong in-plane bonds and weak, van der Waals-like, interlayer coupling. Heterostructures made by stacking different atomically thin 2D crystals provide a platform for creating new artificial materials with potential for discoveries and applications. In this PhD project you will work on advancing fabrication technology to explore the potential of van der Waals heterostructures in photonics. We focus on studies of the strong light-matter interaction in 2D materials embedded in microcavities, opening unprecedented possibilities to explore new physics and device applications. You will join an energetic team of 5 PhD students and 2 postdocs. You will perform advanced optics experiments in the state-of-the-art laboratories of the Sheffield group, work on novel device fabrication in the modern clean room and collaborate with leading groups around the world on 2D physics and technology. See further details at http://ldsd.group.shef.ac.uk/research/2d-materials/
|Single photon emitters in atomically thin 2D semiconductors for quantum technology applications||Following the discovery of graphene a large family of layered crystals has attracted significant attention. Surprisingly, single photon emission was found in several 2D semiconductors from unusual defect states. It was then shown that such defects can be prepared at will, opening a new class of materials with a potential for quantum technologies, where single photon emitters (SPEs) are at the core of communication and computing schemes. In this PhD project you will work on advancing fabrication technology for the SPEs and importantly will devise the methods for their integration in photonic structures such as microcavities, waveguides and photonic crystals. You will join an energetic team of 5 PhD students and 2 postdocs. You will perform advanced optics experiments in the state-of-the-art laboratories of the Sheffield group, work on novel device fabrication in the modern clean room and collaborate with leading groups around the world on 2D physics and technology. See further details at http://ldsd.group.shef.ac.uk/research/2d-materials/
Keywords: condensed matter physics, materials science, optical physics, semiconductors, photonics, quantum technologies, 2D materials, graphene, MoS2
|Optical Quantum Information Processing||
Information processing with light is ubiquitous, from communication, metrology and imaging to computing. When we consider light as a quantum mechanical object, new ways of information processing become possible. We can use quantum nonlocality (entanglement) to perform secure communication, high-precision measurements, high-resolution imaging, and even build a quantum computer that can perform certain important tasks much more efficiently than ordinary computers. A PhD in optical quantum information processing at the University of Sheffield can touch on any, some or all of these topics. We are investigating how quantum repeaters can extend the reach of quantum communication protocols and may some day lead to the Quantum Internet. We study how arrangements of light emitters can be used to monitor deformations of the material upon which they are placed with exquisite precision and how quantum measurement techniques can be used to measure very precisely the shape and size of objects. We are developing new ways of creating entanglement and nonlocality between atoms and photons in waveguides and on chips. This will allow us to reliably create the necessary resources for a large-scale quantum computer that can be connected to the Quantum Internet.
|Theory of Quantum Microcavity Polaritons||
Microcavities are dielectric structures which trap electromagnetic fields in a very small region of space. When this field is made to interact with a semiconductor material, the excitations of the system are 'particles' known as polaritons. Polaritons have many interesting properties; they undergo a condensation similar to a BEC, which shows behaviour analogous to a superfluid. In this project, we shall be looking at the quantum mechanical properties of the polariton condensate to investigate whether it can show interesting quantum optical behaviour such as squeezing. Although the project is theoretical, involving analytical and computational work, there is a strong experimental polariton activity in the department, providing plenty of opportunities to collaborate in developing quantum optical technologies. This project will suit a physics graduate with good mathematical abilities and some background in computational work.
Quantum computing with new error correcting codes
Quantum systems can store and process quantum information, opening up the prospect of new technologies that outperform conventional supercomputers in many areas. However, quantum information is more fragile than classical binary information, being more susceptible to noise and rapid degradation. To build a reliable device, quantum information must be stored within an abstract quantum codespace that protects it against noise. Quantum computers must also tolerate faults occurring while processing information. In this project, you will develop new techniques for fault-tolerantly storing and processing quantum information, using both analytic and numerical methods to assess their performance. Quantum codes investigated in this PhD will include so-called topological codes (using notions of topology and homology) and more general low-density parity check codes (using graph theory tools such as expander graphs). I am looking for an enthusiastic student with a physics, mathematics or computer science degree. Additional skills that are desirable, but not essential, include: a good undergraduate-level understanding of quantum mechanics, a strong mathematical background and/or experience programming and running numerical simulations (e.g. in C or python). If you are thinking of applying and want to know more about the project, then please email me at email@example.com.
|Nanowire quantum dots for novel quantum emitters||
Using advanced semiconductor epitaxial growth techniques it is possible to fabricate long, thin semiconductor wires with length exceeding 1µm and diameter less than 30nm. Inserting a small disk of a lower bandgap semiconductor within these nanowires produces a zero-dimensional structure, a quantum dot (QD). QDs have a number of unique properties and have been used to produce high efficiency lasers, sources of single photons and as elements suitable for quantum computing. Nanowire QDs offer a number of advantages over more conventional self-assembled QDs but are still a relatively immature field of study. The project will involve the study of physical processes in nanowire QDs using state-of-the-art optical spectroscopy. Working with groups at University College London and Warwick University the ultimate aim is to obtain a full understanding of the physical, electronic and optical properties of these novel structures and develop single photon sources and nanoscale lasers.
|Nonlinear and quantum polaritonics||
Recent advances in semiconductor nano-technology lead to a new generation of robust controllable structures where manipulation of coupling between light and matter can be performed on a submicrometer scale. In these structures novel quasiparticles-polaritons, which are a mixture of light and matter (electrons), can be created. Polaritons have very small effective mass and, thus, may condense in a single quantum state at high temperatures. This macroscopically occupied state has properties similar to those of atomic Bose-Einstein condensates. In addition, giant polariton-polariton interactions may results in a number of phenomena ranging from superfluidity of light, ultra-low power self-localised wavepackets (solitons) to generation of single photons and entangled photon pairs. Polariton physics in microcavities is very topical research which may find future applications in quantum optical computation. A particular emphasis in this project will be placed on optical experimental studies with the aim to control temporal and spatial phase information, and spin and statistical properties of polaritons in different geometries.
A successful candidate will join a well-funded and very active research group with a world-wide reputation for excellence (https://ldsd.group.shef.ac.uk/research/polaritons/). The group possesses a wide range of modern equipment to conduct advanced quantum optics experiments. During the project the student will also obtain full access to a state-of-the-art clean room facilities available in Sheffield.
|Computational projects to investigate novel magnetic phenomena in oxides||
A new research area is developing called Spintonics. This means that it is electronics in which both the charge and the spin of the mobile electrons play a role. There are good reasons why the situation that has existed in which the power of conventional electronics increases every year is going to end fairly soon. Spintronics is very likely to become the new vital technology in the future. Hence there is a large interest in this topic worldwide. The standard magnetic materials such as iron and cobalt are not always most suited for integrating with semiconducting devices and so there is an increasing interest in understanding oxide magnets. This has been the focus for an experimental programme in Sheffield for many years. Modern supercomputers have enabled increasingly sophisticated modelling of heterogeneous materials so that modelling of these materials becomes feasible. There are two effects that occur when nanoparticles are incorporated into oxide materials. One is that the magnetism is very strongly enhanced and the other is that the materials can exhibit two different resistance states where a low resistance state is initiated at high voltage but remains stable until a significant reverse voltage is applied. Thus there are two projects in this area both of which will use the same set of modelling codes, CASTEP, one is to investigate the magnetic properties and an oxide in contact with metallic cobalt nanoparticles and the other is to model current flow through an oxide-nanoparticle array. However electronic modelling only takes one so far and there is always a need to combine this with theoretical insights. If you want to know more about these projects then please contact me at firstname.lastname@example.org.
Particle physics and particle astrophysics
Our experimental work falls into four main categories: experimental high energy physics, the search for dark matter, neutrino astrophysics, and neutrino physics, including neutrino factory research and development.
|ATLAS: Search for additional Higgs bosons||
The discovery of the Higgs boson by the ATLAS and CMS experiments at the LHC in 2012 has completed the particles predicted by the Standard Model (SM).
Nevertheless , the SM cannot be the end of the story for fundamental particle physics, as it leaves unanswered many questions, such as the lack of stability for the mass of the Higgs boson (the hierarchy problem), and an explanation for the Nature of dark matter and dark energy which seem to dominate in the Universe.
Many well motivated Beyond the Standard Model models (Supersymmetry, 2 Higgs Doublet models), predict the existence of extra heavier Higgs bosons. Different BSM models predict different production and decay rates, of these extra Higgs bosons to known particles, depending on the values of a few parameters. Therefore, to successfully discover or exclude these models a combination of different SM-like Higgs final states (e.g H->tau tau, H->4l , H->bb, H->\gamma \gamma etc) and unique BSM decays predicted or enhanced in BSM theories (e.g. A to Zh and H to hh) is imperative.
The focus of this project will be to either observe or put limits on the production rates of extra higher mass “heavy” bosons predicted by theories beyond the SM. The extracted results can be then interpreted in the context of BSM benchmark scenarios like hMSSM or Mhmod. The proposed search for extra Higgs bosons currently constitutes a major probe for physics beyond the SM in the LHC.
|ATLAS: Searching for Di-Higgs Boson Production||
It's possible that the 125 GeV Higgs boson discovered by the ATLAS and CMS Experiments is only one of several neutrally-charged Higgs bosons predicted by theories beyond the Standard Model. Many of these theories predict the existence of a more massive Higgs boson, H, that is able to decay into two lighter 125 GeV Higgses. The student will develop analysis strategies to search for the production of two neutral 125 GeV Higgs bosons (H to hh), and then carry out these search strategies on the ATLAS Run-II 13 TeV collision data. Searches will focus on a final state where one of the Higgs bosons decays into two tau leptons, and the second Higgs boson decays to a pair of bottom quarks. The student will also use this same final state to explore the Higgs boson self-coupling (h to hh). The student will participate in developing algorithms for tau lepton identification, and will also be expected to play a role in the development of silicon module hardware for the ATLAS tracker Upgrade.
|ATLAS: Search for supersymmetric partners of the bottom and top quarks||
The student will develop an analysis to search for supersymmetric partners of the bottom- and top-quarks with ATLAS and will apply them to the latest data from the experiment. The project will focus on events where two b-quarks are reconstructed together with large missing transverse momentum. This channel offers the best possibility for discovering sbottom and stop squarks at the LHC, with stop squarks themselves expected to be significantly lighter, and hence more observable, than other strongly interacting SUSY particles. This project therefore offers the student the possibility of making a Nobel prize winning discovery!
|ATLAS : Measurement of dibosons and searching for new physics||In general, measurements of diboson production can give hints of new physics and precise measurements of them can be combined to yield the best constraints on the electroweak Lagrangian describing the interaction between the W,Z and the Higgs bosons, directly relating to the nature of the electroweak symmetry breaking.
There is three main ingredients to the project, first obtaining of ATLAS authorship, second is contribution to a measurement, either pp->WW production with advanced analysis methods or exclusive yy->WW production and the third is the combination of those with other measurements in order to search for new physics.
|CYGNUS - Global Search for Dark Matter Particles with Directionality||
Sheffield is a key player in the world-leading dark matter experiment CYGNUS that is seeking a unique directional signal for Weakly Interacting Massive Particles (WIMPs), the favoured candidate to explain the missing dark matter of the Universe. CYGNUS involves the merging of multiple groups around the world to form a new collaboration that aims to produce a network of directional detectors with capability eventually to reach below the so-called neutrino floor and to provide a definitive signal to prove that WIMPs exist in the galaxy. The thesis project will focus on development of new detector R&D using optical and gas charge readout technology for CYGNUS plus operation of the working DRIFT II directional experiments, including analysis to search for dark matter candidates and development of new techniques for track reconstruction. DRIFT is sited at the UK’s new deep underground laboratory at Boulby. Collaborating countries in CYGNUS include China, Australia, USA, Italy and Japan. For CYGNUS there will be opportunity participate in tests with new devices at Boulby and sites across these countries.
|Particle Detectors for Medicine using Liquid Argon||
The Sheffield particle physics group is developing liquid argon technology for neutrino and dark matter particle physics. However, this technology can also be of use in medical nuclear physics, in particular for positron emission tomography (PET). This project will involve use of our dedicated liquid argon detector test facility at Sheffield to study new scintillation imaging gas photomultipliers and related charge and light readout technologies with a view to optimizing these for medical imaging applications including PET. The project will also involve development of GEANT4 and other detector simulations to back up the experimental work. The project is suited to applicants with a strong physics background.
|Particle Detectors for Muon Tomography applied to Climate Change||
The particle physics group at Sheffield is developing new uses for muon detector technology that has emerged from our work in dark matter and neutrino physics. The focus in this project will be on development of novel detectors for muon tomography to allow monitoring of CO2 stored deep underground. This is part of global efforts on carbon capture and sequestration (CCS) as a means to combat climate change. The project involves collaboration with geo-physics groups and development of new instruments to be installed and tested using the UK’s deep underground science laboratory at Boulby. The work will involve design, construction and operation of new muon tomography devices as well as simulations and data analysis for CCS.
|RATRACK - Directional Sensitive Nuclear Recoil Detectors for Homeland Security and Environmental Radon Assay||
The Sheffield particle physics group is acknowledged by the UK research council STFC as having one of the best programmes of spin-out activity designed for using particle physics technology in industry and for society. RATRACK is a novel gas-based particle detector spin-out technology with CCD cameras, developed from dark matter work, turned to allow 3D imaging of alpha particles and nuclear recoils induced by fast neutrons. The project involves design and optimization of a next generation device that can be used to do very sensitive measurements of environmental fast neutrons, including their direction, but also to allow assay of environmental radon or surface alpha contamination. The project involves international collaboration with groups in Italy, Australia and the US as well as links with industry.
|DUNE – Design and Optimisation of The Deep Underground Neutrino Experiment at Fermilab for Low Threshold Operation||
DUNE is the a billion dollar international neutrino experiment in which a beam of neutrinos will be fired from Fermilab, USA to a 10 kton liquid argon detector built 1300 km away in a new underground facility at Homestake, S. Dakota. Construction has already begun but one issue to address is the ability of DUNE to detect low energy non-accelerator events, such as from possible proton decay or astrophysical neutrinos. The project will involve a combination of experimental work to measure and understand the critical low background performance of the DUNE detector components, specifically radon emanation and U/Th issues, plus simulations and analysis to assess the implications of this on the design and science capability for low energy physics. There will be chance for long term attachment (6-12 months) in Chicago at Fermilab. This a rare chance to become integral to work towards the huge DUNE experiment in the US, gaining both hardware and software expertise.
|ProtoDUNE – Test Experiment for the Deep Underground Neutrino Experiment DUNE - Optimisation and Data Analysis||
ProtoDUNE is a 770 ton liquid argon detector being constructed at CERN as a test-bed for the huge DUNE experiment, a billion dollar international neutrino experiment in which a beam of neutrinos will be fired from Fermilab, USA to a 10 kton liquid argon detector in the Homestake mine, S. Dakota. This project will focus on optimization of the central Anode Plane Array (APA) detectors that are key to ProtoDUNE and have just been built by Sheffield with other groups. The project involves final commissioning and operation of the APAs at CERN, developing simulations of the final detector and analysis of particle beam data with a view to aiding the final design of DUNE itself. This includes study of electron lifetime performance and low energy performance. There will be opportunity for involvement in operations of ProtoDUNE at CERN and a chance for long term attachment at CERN or Fermilab (6-12 months).
|SBND – Sterile Neutrino Search with the Short Baseline Neutrino Detector Experiment at Fermilab||
The Short Baseline Neutrino Detector (SBND) at Fermilab is a 100 ton liquid argon detector that is part of a suite of three new detectors based on new technology using liquid argon, sited in a neutrino beam at Fermilab. Sheffield has played a leading role in construction of this new experiment, including contributing to design and construction of the main Anode Plane Arrays (APAs). SBND is due to start full operation in 2018/19. The project will focus on analysis of data in the area of searches for sterile neutrino events and the relationship to the dark matter problem. This includes development of LARSOFT simulations. There will be opportunity to contribute to final installation activities, detector optimization and operation. The project offers a rare chance in neutrino physics to gain experience of both detector hardware and operation as well as data analysis towards new physics. There will be chance for long term attachment (6-12 months) in Chicago, Fermilab.
|ARGONCUBE – Design, Construction and Test of the Liquid Argon Near Detector for the DUNE Neutrino Experiment||
In association with the giant 10 kton DUNE (Deep Underground Neutrino Experiment) being built at Homestake there will need to be a smaller near detector at Fermilab. The Sheffield group is collaborating with Bern University to build and test a liquid argon version of this with responsibility to design, build and test a 1.0m x 0.5m time projection chamber device. The project involves contributing to the design, installation and operation of this with Bern colleagues in Switzerland and subsequent analysis of particle data following transfer to a test beam at CERN or Fermilab. There will be opportunity also to conduct support detector R&D using the Sheffield liquid argon test-stand facility to study upgrade options for the readout, including comparison of silicon photo-sensors, cryogenic photomultipliers, GEMs and micromegas devices. Critical measurements are anticipated of liquid argon parameters including electron drift. There will be chance of long term attachment (6-12 months) in Bern or at CERN in Switzerland.
|DM-ICE and COSINE-100 - Search for Dark Matter Annual Modulation||
The Sheffield group is participating in the search for a galactic particle dark matter signals using the so-called annual modulation signal with the DM-ICE experiment 2.5 km below the South Pole and as part of the new COSINE-100 experiment on South Korea. Sheffield built the two NaI(Tl) scintillation detectors now running in the DM-ICE17 experiment. Recently DM-ICE has joined forces with groups across Asia to form the COSINE-100 that has just started operating 100kg of NaI. The project will focus on analysis of remaining data from the 17 kg prototype scintillator in the ice and new COSINE-100 data to search for a dark matter annual modulation signal. There will also be opportunity to contribute to design and test of the new crystals being developed for an upgrade to a 250 kg ultra-low background detector. Part of this work includes use of test facilities the UK’s Boulby underground site. There will be opportunity to participate in deployment activities in South Korea and possibly at the Antarctic South Pole.
|WATCHMAN – Nuclear Non-proliferation Detector Development||
The Sheffield group is playing a leading part in a US-UK collaboration to establish a 1 kton neutrino detector based on water Cherenkov that can be used as a remote monitor of nuclear reactor operations. Such a device has unique capability to determine the reactor cycle and state of a remote reactor, of importance for possible nuclear non-proliferation applications. The student would be involved in simulations and detector development around research to optimise the sensitivity of such a device. This includes work to optimise the light collection and find a cost optimum for the experiment for installation in the UK’s deep underground science facility at Boulby, which is close to the Hartlepool civil reactor. This a unique project that combines fundamental neutrino physics with contributions to humanity through participation in nuclear non-proliferation activity designed to reduce the likelihood of nuclear material production for non-civil uses.
|Studying Neutrino Oscillations with the T2K Experiment||
The Sheffield T2K group are currently involved in analyses of so-called CCpi0 events, i.e. charged current events that contain one neutral pion, an important channel when understanding electron neutrino appearance systematic errors. The group also has responsibility for timing calibration in the ND280 detector. The student will also have the opportunity to spend longer periods of time (typically 6-12 months) out at J-PARC where they will participate in shift work on the T2K ND280 near detector at J-PARC in Japan.
|Muon tomography for nuclear waste characterisation||
The studentship will focus on the application of muon tomography to the characterisation of nuclear waste. The student will be a member of the EU Horizon 2020 funded CHANCE project which involves government agencies, national labs, universities and industrial partners across Europe.
The work will be a mixture of experimental work and software based studies. The hardware aspect will focus on detector construction, deployment and commissioning of a muon tomography detector system in collaboration with colleagues from the University of Bristol in the UK. There will also be the need to perform simulations of the experiments using the GEANT and/or MCNP software packages and the opportunity to analyse the data taken with proxy and real nuclear waste drums.
The work will involve travel to Europe and there is the possibility of placements at CHANCE partners, including the Jülich Research Centre, Forschungszentrum Jülich (see http://www.fz-juelich.de) during the period of study.
If you have any questions about this project please contact Professor Lee Thompson at email@example.com.
|Calibration of the HyperKamiokande neutrino detector||
HyperKamiokande is a next-generation water Cerenkov neutrino detector that is planned to be built in Japan over the next 10 years. HyperK will play an important role in measuring the parameters in the PMNS neutrino mixing matrix and in determining whether or not we observe CP violation in the neutrino sector. A huge detector such as HyperK requires various calibration systems in order to fully understand aspects such as PMT characteristics and the properties of the water (scattering, absorption, etc.). The Sheffield group are involved in the design and testing of a calibration system based on the injection of short-duration light flashes from pulsed LEDs. This PhD will involve considerable experimental work, both at Sheffield and in Japan where a prototype calibration system will be deployed in the SuperKamiokande detector in 2018/19.
|WATCHMAN: an anti-neutrino detector for nuclear non-proliferation studies||
The WATCHMAN project involves a joint US-UK collaboration of universities and national labs who are working to design and build an anti-neutrino detector deep underground that will monitor anti-neutrinos from nearby nuclear reactors. The ultimate goal of the project is to develop a tool that can be used in nuclear non-proliferation applications. This PhD will involve both computational and experimental work. The former will involve simulations of the sensitivity of the proposed detector and the assessment of the effect of backgrounds (e.g. cosmic-induced or natural radioactivity) to the performance of the detector. The expected time scale for the construction of WATCHMAN and the start of data-taking falls within the duration of this PhD (approximately 2019). Therefore, the experimental work will involve building, calibrating, and running the detector, as well as an analysis of the first reactor anti-neutrino data.
|Neutrino Oscillation Measurements with T2K||
T2K is a long-baseline neutrino oscillation experiment based in Japan. The aims of the experiment are to improve the understanding of muon neutrino oscillation (to both electron neutrinos, 1-3 mixing, and tau neutrinos, 2-3 mixing) and to constrain the CP-violation parameter delta. The student will contribute to neutrino oscillation measurements either directly or by studying processes that contribute to the systematic error in the oscillation measurements. This project is likely to involve spending a significant amount of time (6-12 months) in Japan.
A dominant cause of systematic errors in neutrino oscillation measurements is our current lack of a good description of the neutrino-nucleus cross-section. Building on past experience within the Sheffield T2K group, the student will work on improving the description of neutrino-nucleus interactions in the simulations used in T2K and other neutrino experiments. This will involve developing an understanding of the physical processes involved and how they are implemented in the simulations, and using data from T2K and other neutrino experiments to tune the models to improve their description of the data.
|Supernova Neutrinos in TITUS and Hyper-K||
The Hyper-Kamiokande experiment is a proposed extremely large (Mton scale) water Cherenkov neutrino detector in Japan. Hyper-K will act as the far detector for a proposed next-generation neutrino oscillation experiment, but also has a strong research programme in non-accelerator neutrino physics. One area in which Hyper-K has good potential is the study of neutrinos from the next Galactic core-collapse supernova. The student will work on implementing the most up-to-date models of core-collapse supernovae in the Hyper-K simulation and investigating the sensitivity to the properties of both neutrinos and supernovae offered by the detection of a hypothetical supernova at a distance of order 10 kpc. (A real Galactic supernova cannot, unfortunately, be guaranteed on the timescale of a PhD studentship...)
|Gravitational Wave Searches with LIGO/GEO600/Virgo||
The HEP group at Sheffield includes an active experimental gravitational wave research group, consisting of two faculty members, a postdoctoral researcher, and two current Ph.D. students. We are members of the LIGO scientific collaboration, and are active in detector commissioning, detector characterisation and data analysis in connection with the LIGO, Virgo, and GEO600 gravitational wave interferometers. In addition, we have a strong role in the GOTO dedicated gravitational-wave optical follow-up instrument, aiming at detecting optical counterparts to gravitational wave signals. Ph.D. projects in the group include gravitational wave data analysis, particularly fast real-time analysis pipelines and work with the electromagnetic follow-up group within LIGO, and the GOTO optical follow-up project. Advanced LIGO is due to come on-line for first science data in 2015, so this is an exciting time to be involved in gravitational wave interferometery.
|Dark Matter Search with the LZ Experiment||
LUX-ZEPLIN (LZ) is a project to build and operate a high-sensitivity dark matter experiment in the deep mine at SURF (South Dakota, USA) able to probe most of the WIMP parameter space region free from astrophysical neutrino background. The PPPA group at the University of Sheffield is involved in the LZ experiment with a prime responsibility for developing software for modelling and data analysis, simulating background radiation and detection of various particles. The construction phase has been started in 2015 and it is a good time for a PhD student to be involved in the project. The PhD project will include Monte Carlo modelling of the LZ experiment including its background and detector response, and development of the analysis code and other software tools in preparation for the data analysis. The student can also contribute to the detector construction and tests of different parts, as well as to the measurement of radioactive contaminations in different materials. There is an opportunity to spend 6 - 12 months in the USA and be involved in detector assembling and commissioning. The successful candidate should have a good knowledge of particle physics and programming skills. The knowledge of nuclear physics and particle astrophysics is desirable. The LZ detector will operate from 2020 for at least 5 years so the PhD student will analyse the first data from the experiment.
|Neutrino Oscillation Study and Proton Decay Search with DUNE||
DUNE is a large international project to design, construct and operate a multi-kiloton scale liquid argon detector for neutrino physics, astrophysics and proton decay search. The detector will be built deep underground at the SURF facility (South Dakota, USA). The PPPA group is involved in the DUNE project with one of the responsibilities to model background events produced by cosmic-ray muons and investigating the sensitivity of the experiment to different tasks. This PhD project includes Monte Carlo simulations of muons and muon-induced cascades for different detector designs, studying discrimination between signal and background events and evaluating detector sensitivity. The student will also be expected to contribute to the data analysis and calibration of SBND (Short-Baseline Near Detector) to be installed at Fermilab in 2018 with a goal to test some neutrino oscillation anomalies reported by several experiments and search for sterile neutrinos. Another potential task within this PhD project is the calibration and analysis of data from ProtoDUNE - the small prototype of DUNE to be built at CERN in 2017. There is an opportunity to spend 6-12 months at Fermilab or at CERN working with the SBND or ProtoDUNE detectors. The candidate should have a good knowledge of particle physics and programming skills. The knowledge of nuclear physics and particle astrophysics is desirable.
|Cosmic-Ray Muons in Different Applications||
Cosmic-ray muons are known to be useful in applications beyond particle astrophysics. They have helped to map structure of volcanoes and finding voids in various geological structures. Other possible applications include studies of geological repositories including monitoring carbon capture, tracing illicit nuclear materials etc. The PPPA group at the University of Sheffield, in collaboration with other institutions and industrial partners, pursues a wide programme related to these muon applications. This PhD project offers an opportunity for a student to apply the knowledge of particle/astroparticle physics and detector technology, in other areas which are linked to key problems of the contemporary world: atmospheric pollution, climate change, nuclear security etc.
|Testing Grand Unificiation: Do Protons Decay?||
Grand Unified Theories (GUTs) postulate the merger of the strong force with the electroweak force at energies around 10^16 GeV. This is a trillion times greater than the center of mass energy at the Large Hadron Collider. Proton decay would provide evidence of GUTs, as the proton is stable within the Standard Model but permitted to decay in a Grand Unified context. The Hyper-Kamiokande experiment is a proposed megatonne water Cherenkov detector to be situated in Japan. Its extremely large volume makes it sensitive to proton decay; this sensitivity may be enhanced by a factor of ten if a small amount of gadolinium (0.1%) is added to identify the atmospheric neutrinos that can fake a proton decay signal. The ANNIE experiment at Fermilab will use Gd-loaded water to measure neutron multiplicity and pioneer this technique. The student will measure neutron yield in neutrino interactions at ANNIE, then use these results to model proton decay at a Gd-enhanced Hyper-Kamiokande. The project is likely to involve spending 6 - 12 months at Fermilab (Chicago) and short-term visits to Japan.
|Why Are We Here? - Using Neutrinos to Understand the Matter / Anti-Matter Asymmetry||
If we assume that the laws of physics are the same for matter and for anti-matter, then equal amounts of each should have been created in the Big Bang... and annihilated soon after. Clearly, this did not happen and our observations tell us that we live in a universe composed almost entirely of matter, with virtually no primordial anti-matter remaining. The reasons for this are not clear, but may be explained by violation of the 'charge-parity' (CP) symmetry for neutrinos. The first phase of the Tokai-to-Kamioka (T2K) experiment has seen initial hints of CP violation, which will be probed further during the second phase of operation (T2K-II) and with the proposed Hyper-Kamiokande experiment. T2K is a long-baseline neutrino oscillation experiment, located in Japan, which produces a beam of muon neutrinos. The neutrinos are measured with a multi-stage near detector after 280 meters of travel, and again with a 50,000 tonne water Cherenkov far detector after 300 km. Simulations have shown that our potential for discovering CP violation can be greatly improved by constructing an intermediate-distance kilotonne-scale water Cherenkov detector. Such a detector has been proposed and it is expected to be constructed within the time-scale of this PhD position. This is an experimental PhD with significant components of simulation and data analysis. The student will travel to Japan to participate in the construction and commissioning of the new detector. Once the detector is completed, the student will collect and analyse data within the context of the T2K-II search for CP violation, as well as simulating its effect on the sensitivity for the future Hyper-Kamiokande experiment.
|Light Sterile Neutrinos: Reality or an Experimental Error?||
In recent decades, a variety of experiments have measured anomalies that may be indications of a fourth neutrino flavour. In contrast to the three known 'active' neutrinos, this fourth flavour would be 'sterile', with no couplings via weak interactions. The mass square difference between the active flavours and the sterile neutrino, measured from these anomalies, is approximately 1 eV^2, which is greater than the mass square difference amongst the three active neutrinos. There is no a priori theoretical motivation for sterile neutrinos to exist at this mass. Thus, if these experiments are correct, the existence of a sterile neutrino would be exciting physics beyond the Standard Model. However, it is worth nothing that all of the experiments to see indications of this phenomenon are single detectors acting alone. Therefore, it is also possible that the various anomalies may be explained via uncertainties in the neutrino flux or nuclear effects. To properly confirm (or refute) the existence of a light sterile neutrino, it is necessary to construct an experiment with near and far detectors; a comparison of measurements would cancel such uncertainties. The Short-Baseline Near Detector (SBND) is part of the Fermilab Short Baseline Neutrino (SBN) programme, which will use three experiments to make such a comparison. One of the experiments, MicroBooNE, has already started operation; SBND is expected to commence data taking in 2019. The student would have the opportunity to participate in detector construction and to participate in the existing Sheffield efforts on SBND analysis. In collaboration with the MicroBooNE and ICARUS experiment, this PhD position will culminate in a search for evidence of sterile neutrinos. The project offers the possibility of a long-term attachment (6 - 24 months) at Fermilab, near Chicago.
The materials physics group conducts research (both experimental and theoretical) into the physics and applications of polymers, organic-semiconductors, functional nano-particles, biological materials, imaging and instrumentation.
|Ultrafast singlet exciton fission in carotenoids||
In solar cells, the ability to absorb one photon and harvest two electrons can lead to internal quantum efficiencies of up to 200%. This is possible using organic semiconductors via a process known as 'singlet exciton fission' (SEF), where the primary excited state (singlet exciton) can split into two distinct triplet excitons which can both be harvested.
SEF has also been shown to occur in naturally occurring carotenoids such as astaxanthin and zeaxanthin, but we have recently demonstrated that current theory does not adequately describe SEF in these systems.The proposed project will involve using time-resolved ultrafast spectroscopy in Sheffield's new laser facility to study SEF in carotenoids. The main outcomes of the project will be two-fold:
|Ultrafast spectroscopy of single crystal organic semiconductors||
Organic semiconductors are exciting materials. They are not only starting to compete with traditional (opto)electronic materials in device applications, they are also intrinsically sustainable. Solution-processed organic photovoltaics, for example, use ~10 times less energy to produce than any other PV technology and are only made from earth-abundant elements.
Until recently, it was thought that the problem with organic semiconductors was disorder, thought to be a fundamental draw-back of solution-based (i.e. sustainable, low-cost) deposition techniques. Work in the last 4 years has changed this paradigm. Solution-processed highly ordered single crystals now demonstrate field-effect mobilites above 10cm2/Vs. Only 10 years ago such ultra-high mobilities at room temperature in thin organic films would have been considered unachievable by many experts in the field.
These new ultra-high mobility thin films pose a considerable challenge to our understanding of charge and energy transport. They operate in what is known as the 'intermediate coupling' regime where energy and charge transfer can be described as being somewhere between the band-like transfer that occurs in highly ordered inorganic semiconductors and the purely hopping transfer that occurs in very disordered systems.
In this project, you will measure materials from collaborators in Japan using Sheffield's new laser facility to attempt to describe the energy transport and radiative and non-radiative deactivation in the intermediate coupling regime. It is expected that you will collaborate with theoreticians in the USA to develop models to interpret the data.
|Spray-coating perovskite PV devices over curved substrates.||
Conventional PV cells based on the ubiquitous semiconductor crystalline-silicon most often come in the form of flat, rigid and relatively heavy panels. Despite the fact that PV devices can be manufactured on flexible substrates, methods to integrate PV devices onto the surface of non-planar (3-dimensional) objects are not well developed. Whilst the collection of sunlight for power generation in solar-farms or roof-mounted systems is well served by conventional two-dimensional devices, there are a range of applications in which it is desirable to cover the surface of 3D object with PV devices. These include building cladding, and various consumer products embedded with software, sensors and internet connectivity that collect and exchange data. A key objective of this experimental research project is to develop a manufacturing technology that will allow efficient PV devices to be integrated in an unobtrusive fashion over the surface of 3D objects.
Central to this project is the ability to spray-cast functional semiconductors over non-planar surfaces. The materials of interest to this proposal are solution-processable organometal-halide perovskites. A key task for the student will be to develop a toolbox of materials and spray-coating process techniques that can be applied over curved surfaces such as moulded PMMA and polystyrene substrates. The key science challenge to be addressed is to open a sufficiently wide process-window permitting a surface having some degree of surface-roughness to be used as the substrate for a perovskite solar cell. This will involve metrology of various substrates to characterize roughness, and the possible use of spray-coated planarization layers to control roughness. Once a suitable substrate has been developed, the student will then explore the sputter deposition of various metal-oxide coatings onto the substrates onto which they will then spray-coat charge transporting and perovskite layers. Here, the student will follow strategies previously used to fabricate perovskite solar cells onto flexible substrates (making them compatible with moulded plastic substrates), requiring the use of low temperature processes. Typical devices will have an active area of up to 1 cm2. The student will utilize semi-transparent (dielectric / metal /dielectric) top electrodes deposited by thermal evaporation allowing light to be harvested through the device top contact even if the substrate is opaque. Once a reliable process for to fabricate devices on planar substrates has been established, the student will adapt the coating techniques to fabricated devices over curved substrates.
This project is suitable for a student at Masters level (achieving 2.1 or better), having a degree in physics, physical chemistry, materials science or electronic engineering. This student will be part of the Electronic and Photonic Molecular Materials Group at the University of Sheffield (http://www.epmm.group.shef.ac.uk/), and will also be part of the CDT in New and Sustainable Photovoltaics (http://www.cdt-pv.org/).
This position is only open to UK and EU students. International students should only apply if they have already secured a research scholarship".
|Advanced lasers for new generations of optoelectronic devices and computing||
Semiconductor lasers are the backbone of modern optical telecommunications and are also used in an increasing number of applications in engineering, biology, chemistry and medicine. Recently, researchers have developed a new method to generate laser emission; this involves creating 'optical cavity' devices in which light and matter is mixed together, forming a type of ‘hybrid particle’ termed a cavity polariton. When a large number of polaritons are present in the device, a very unusual thing happens – all polaritons become ‘locked together’ and adopt the same energy and move in the same way. This is a widely known process in physics called ‘condensation’. As polaritons are made from light and matter, we can detect such condensates as they emit light. Such light bears many of the properties of laser light, and so this process is called ‘polariton lasing’. The real interest in polariton lasing comes from the fact that it happens with a very low energy input – this might allow us to reduce energy demands in electronics. Furthermore, it is also possible to use polariton condensates to act as media in which we can perform very complicated calculations that cannot be handled by a regular ‘classical’ computer.
In this project, you will develop optical cavities that contain organic semiconductor thin films. In this context, 'organic' means based mainly on carbon, with such organic semiconductors being very efficient sources of light emission at room temperature (think mobile phone displays). Once you have fabricated such cavities using a range of advanced clean-room processing techniques, you will then explore
This project is suitable for a student at Masters level (achieving 2.1 or better), having a degree in physics, physical chemistry, materials science or electronic engineering. This student will be part of the Electronic and Photonic Molecular Materials Group at the University of Sheffield (http://www.epmm.group.shef.ac.uk/).
This position is only open to UK and EU students. International students should only apply if they have already secured a research scholarship".
|Biodegradable and biocompatible materials for bioelectronics||
The need for biocompatible scaffolds that can be integrated into the body to support therapeutic applications requires a number of factors to work in concert. Material must be biocompatible and preferably biodegradable on time scales commensurate with the application (i.e. the time during which they are required), it must mechanically adapt to surrounding tissue (i.e, have an appropriate elastic modulus), and there must be the ability to chemically attach organic electronic components that relay information. This project is a continuation of ongoing work in developing materials for bioelectronic applications in collaboration with colleagues in Cambridge and Italy. A PhD student working on this project will need to learn basic materials technologies for characterising materials, and also the functioning of organic electronic devices as well as understanding relevant physiological questions.
|Deep vs rote learning of physics in Higher Education||
The idealistic aim of teachers in Higher Education institutions is for all graduates to develop a deep understanding of their subject and skill-sets, and yet the modular structure and emphasis on equation-based assessments mean physics students are (unintentionally) encouraged to only learn what is necessary to pass the exam.
A PhD student working on this longitudinal project will first examine the types of learning styles within physics courses at higher education institutions and to assess their effectiveness in learning both skills and core knowledge. In subsequent work they will develop interventions to improve the different learning styles and measure the impact their designed interventions have made. The student will be expected to work with collaborators in different departments with the University of Sheffield and from different institutions within the UK.