Byron Southern

The goal of my research program is to understand the magnetic properties of nanostructured systems. Magnetic properties at surfaces and interfaces, that make up a large fraction of nanostructured and confined materials, can be quantitatively different from those of bulk systems. Due to reduced symmetry, the magnetic anisotropy at a surface or interface can be orders of magnitude larger than in the bulk. This can lead to magnetic frustration and reorientation of the magnetization at the surface and interface. The potential application of these studies to science and technology is far-reaching: information storage, signal processing technologies, magnetic recording and drug delivery.

Research expertise

Frustrated magnets, spin waves and nanomagnetism

Research highlights

The Ir-Mn compounds are one of the most commonly used materials for the pinning layer and the spin frustration realized in the parent fcc compound IrMn3 could be important. I have used Monte Carlo (MC) methods to explore the spin ordering in this system. Degeneracies appear as planes of defects in the 3D system with only near neighbour exchange which leads to multiple values for the zero temperature sublattice order parameters. I have performed spin-wave and inelastic magnetic scattering intensity calculations to include further neighbour exchange interactions. The additional interactions remove the degeneracies. The scattering intensity, S(q,w), contours were calculated for both single crystal and powder sample scenarios and the results have been compared with new inelastic neutron scattering data on powder samples of ordered phase IrMn3 and the effects of longer-ranged exchange interactions are found to be important.

• Publications