Paul Steadman
Beamline for Advanced Dichroism Experiments (BLADE)
Paul Steadman is the principal beamline scientist on I10, the Beamline for Advanced Dichroism Experiments (BLADE). He started his research career looking at the structures of ultrathin magnetic films using surface X-ray diffraction. He later expanded into the measurement of magnetism from thin films. He did research using the technique of resonant magnetic scattering and constructed equipment for the measurement of Kerr rotation. His latest research involves measuring the disorder from thin magnetic films using neutrons and X-rays.
Email: Paul Steadman
Tel: +44 (0) 1235 778156
Beamline I10: BLADE (Beamline for Advanced Dichroism)
Key Research Areas
Magnetic Disorder in Thin Films, Exchange Bias, Interactions and Structure of Stepped Surfaces, Excited States in Nanostructures
Current Research Areas
My current research interests include the chemical and magnetic disorder in rare earth and transition metal films. Layered magnetic devices involving magnetic and nonmagnetic materials, such as those used in read heads for magnetic hard drives are now being made at the nanometre scale. The performance of these devices depends on the disorder in the layers and at the interfaces. Such disorder can come in different forms. There is disorder in the form of magnetic domains, and at the interfaces. This roughness can come in two forms: chemical or magnetic. These different types of disorder can be quantified statistically using specular and off-specular X-ray scattering. One way of obtaining the magnetic component of the roughness is to use circular dichroism scattering. By this technique it has been found that in certain materials the magnetic interfaces are smoother than the chemical interfaces.
Exchange bias is another area of interest. In real materials it is difficult to look at the magnetic structure in antiferromagnetic materials at the interface. A possibility is to grow artificial materials where magnetic layers are separated by nonmagnetic spacers. With certain layers such as cobalt and ruthenium it is possible to tune the magnetic interactions between cobalt layers separated by ruthenium spacers by adjusting the thicknesses of the ruthenium layers. Cobalt layers can therefore be coupled antiparallel (antiferromagnetic) or parallel (ferromagnetic). By growing an artificial ferromagnet next to an antiferomagnet spins in each layer can be probed using neutron reflectometry, of which the spins in the antiferromagnet are of particular interest. Results demonstrated the role of the large anisotropy in the antiferromagnetic layer.
Selected Publications
- Probing Magnetic Ordering in Multilayers using Soft X-ray Resonant Magnetic Scattering, C. H. Marrows, P. Steadman, A. C. Hampson, L. A. Michez, B. J. Hickey, N. D. Telling, D. A. Arena, J. Dvorak and S. Langridge, Physical Review B 72 024421 (2005)
- Magnetic anisotropy of ultrathin cobalt films on Pt(111) investigated with x-ray diffraction: Effect of atomic mixing at the interface, O. Robach, C. Quiros, P. Steadman, K. F. Peters, E. Lundgren, J. Alvarez, H. Isern and S. Ferrer, Physical Review B 71 099903 (2005)
- Resonant x-ray scattering from a magnetic multilayer reflection grating L. Michez, C. H. Marrows, P. Steadman, B. J. Hickey, D. A. Arena, J. DvorakH. L. Zhang, D. G. Bucknall and S. Langridge, Applied Physics Letters 86 (11) 112502 (2005)
- Ultrathin Pt films on Ni(111): Structure determined by surface x-ray diffraction, O. Robach, H. Isern, P. Steadman, K. F. Peters, C. Quiros and S. Ferrer, Physical Review B 68 214416 (2003)
- Exchange bias in spin-engineered double superlattices P. Steadman, M. Ali, A. T. Hindmarch, C. H. Marrows, B. J. Hickey, S. Langridge, R. M. Dalgliesh and S. Foster Phys. Rev. Lett 89 077201 (2002)