Exploring fundamental length scales in nanomagnetic spintronic and data storage materials

The aim of this project is to understand how ferromagnetic ordering is modified as the size of the magnetic particles/islands/grains is reduced to a few nanometers which is the fundamental length scale in magnetically ordered materials. This is a key challenge in realizing real, technologically useful nanomagnetic materials for spintronics devices and data storage. At the nanoscale it is critical to determine the relationship between structure and magnetic properties as non-uniformities, segregation and grain boundaries have a profound effect on material and device functionality.

In order to develop this understanding X-ray and neutron scattering together with transmission electron microscopy (TEM) can be used to probe the structural and magnetic properties at less than 1 nm. In particular, neutron and x-ray scattering using the brilliant sources and high resolution instruments available large facilities have opened an exciting new world of discovery not available from laboratory based instrumentation. Specifically, in this project small angle x-ray (SAXS) and small angle neutron (SANS) scattering, allied with TEM will provide the most detailed understanding as to how structure dictates magnetic properties in materials and devices of significant technological promise1. The large scale facility measurements are typically carried out at the Diamond light source, ISIS neutron scattering facility and the Paul Scherrer Institut in Switzerland which will also provide an excellent opportunity to interact with researchers from across Europe. An integral part of this project will be the opportunity to contribute to our research on magnetic vortex oscillators2 where the interplay of thin films with different magnetic anisotropies results in new methods of controlling vortex structures.

Initially, research work for this project will focus to two systems, (i) arrays of lithographically defined magnetic islands and (ii) hybrid anisotropy structures for vortex oscillators. Essentially, there are three activities associated with this research project that provide a wide range of experience:

• Fabricating materials and structures
• Measurement using X-Rays, neutrons and electrons
• Analysis of data and development of models

as this is part of our on-going research work there is significant flexibility for the student to develop their own interests within these broad topics.

Since this project addresses one of the critical challenges in moving forward the science and technology of magnetic materials, we expect that there will be opportunities to work with the data storage industry within our existing collaborations. In short the research work in this project will make a leading-edge contribution to understanding the fundamental physics of nanoscale magnetism in materials and systems that are likely to be key technology components in future devices.

1S.J. Lister et al. APL 97 (2010) 112503
2G. Heldt et al. APL 104 (2014) 182401 (Applied Physics Letters - Front cover 5 May 2014)