Dr Matthew Bryan
MSci, PhD
Research Associate (SCAMMD)
Address:
Department of Materials Science and Engineering
Sir Robert Hadfield Building
Mappin Street, Sheffield, S1 3JD
Telephone: +44 (0) 114 222 5944
Fax: +44 (0) 114 222 5943
Email: m.t.bryan@sheffield.ac.uk
Matthew Bryan obtained his MSci in Physics from Durham University in 2003 and continued at Durham to begin a PhD under the supervision of Russell Cowburn. In 2005, he moved to Sheffield after Cowburn’s group split between Durham, Imperial College and Sheffield, and began a PhD under the supervision of Dan Allwood. He completed his PhD on “Nucleation and propagation of domain walls in Permalloy nanostructures” in 2008, winning the Brunton medal for an outstanding thesis. Following this, he undertook a one-year PDRA with John Haycock, to test the feasibility of aligning Schwann cells using superparmagnetic beads and patterned microstructures. Matthew’s current PDRA position is collaboration with the University of Leeds and Seagate, looking at potential read-elements for the next generating of hard disk drives.
In addition to research, Matthew has an interest in teaching and outreach. In 2009, he won the Kroto Family Science Education Prize for an outreach project at King Edward VII school in Sheffield. The project involved teaching students about magnetic energies, introducing them to computational modelling and guiding them through a research project, culminating in a publication in the Journal of Applied Physics. Other teaching projects include regular tutorials on magnetic modelling for an MSc course and the filming of training videos for teaching lab skills.
Research interests
My work can be divided into three areas: the fundamental physics of magnetic wires, the effect of combining magnetic layers with other materials and the application of magnetic beads. Some of this work involves collaborations outside of my current PDRA project, working with various people throughout the University of Sheffield, including Dr Julian Dean, Dr Stephen Ebbens, Dr Martin Grell and Dr Jonathan Howse.
The first research area involves magnetic wires with widths of around 100-500 nanometres and thicknesses around 5-20 nanometres (a nanometre is a billionth of a metre). This provides fundamental information about how the magnetic poles of the magnet may be switched in the presence of a magnetic field. Essentially, a magnetic pole moves from one end of the wire to the other, creating an opposing pole as it leaves. Structural features in the wire, such as notches, and the strength of the applied field enable the speed and position of the pole to be controlled.
This research informs study of the effect of combining magnetic layers with other materials. Interactions between the different layers can lead to properties that are difficult to achieve in single-layer systems. For example, magnetic switching may be achieved using an electric field, rather than a magnetic field, if the magnet interacts with a piezoelectric material. Typically, the interactions work both ways, allowing the magnet to influence the properties of the other material, potentially allowing remote activation of properties.
Another application of the remote operation achievable using magnetic fields is in manipulating magnetic beads. Commercially available beads come in a variety of sizes and may be coated with different materials for particular chemical or biological functions. The ability to manipulate the beads using magnetic fields provides additional control which can enhance potential applications.
Current research
My current project involves the patterning of magnetoresistive stacks in close proximity to Permalloy nanowires. The resistance of the stacks depend on the magnetic field from the nanowires, so can be used as a remote sensor of the nanowire magnetization. This work compliments previous work, which has shown that nanowires can be used to store and process data, by showing that the data can be read electrically, allowing integration of magnetic- and semiconductor-based devices.
Key publications
- J. Dean, M. T. Bryan, T. Schrefl, and D. A. Allwood, Stress-based control of magnetic nanowire domain walls in artificial multiferroic systems, J. Appl. Phys., 109, 023915 (2011).
- M.T. Bryan, J. Dean, T. Schrefl, F.E. Thompson, J. Haycock, D.A. Allwood, The effect of trapping superparamagnetic beads on domain wall motion, Appl. Phys. Lett., 96, 192503 (2010).
- M. T. Bryan, K. H. Smith, M. E. Real, M. A. Bashir, P. W. Fry, P. Fischer, M. Y. Im, T. Schrefl, D. A. Allwood, and J. W. Haycock, Switchable Cell Trapping Using Superparamagnetic Beads, IEEE Magn. Lett., 1, 1500104 (2010).
- T. J. Hayward, M. T. Bryan, P. W. Fry, P. M. Fundi, M. R. J. Gibbs, D. A. Allwood, M.-Y. Im, and P. Fischer, Direct imaging of domain-wall interactions in Ni80Fe20 planar nanowires, Phys. Rev. B, 81, 020410(R) (2010).
- M. T. Bryan, T. Schrefl, D. Atkinson, and D. A. Allwood, Magnetic domain wall propagation in nanowires under transverse magnetic fields, J. Appl. Phys, 103, 073906 (2008).