Fermiology and spin densities from x-ray scattering

Magnetism plays a fascinating role in the properties of many materials. As well as being able to create an external magnetic field that can be observed or used, magnetism can determine other properties of the material itself. In our project we will be studying materials where the underlying physics behind these magnetic properties is as yet poorly understood. We will also making accurate measurements of property known as spin polarisation, in materials that could be of use for technological development in the future. The other main aspect of our work is to perform experiments that should contribute to our understanding of superconductivity. In our project we will study a set of these materials where there is currently significant controversy surrounding the underlying electronic structure, with different results being found using different experimental techniques. Our experiments will help to resolve these problems.

In order to provide the sensitivities required, these experiments all require us to use x-rays to measure specific details of the magnetic properties. The only way to obtain x-rays of sufficient intensity and with the particular properities required, is to use a synchrotron source. There are a few of these available world-wide. The choice of synchrotron for these experiments was based on the particular experimental facilities and x-ray energy available at the SPring-8 synchrotron in Japan.

Impacts on knowledge :
Magnetism and superconductivity are two of the strongest and most important themes
in current physics research. Our research is aimed towards providing insight into
both of these areas at the fundamental level, and the techniques we will develop for
probing, for example the spin-polarisation in spintronic materials, will hopefully
have substantial impact. Similarly, the work on the electronic structure of high-temperature
superconductors is aimed at resoliving a long debate regarding the nature of the
normal state.

Impacts on people:
The major resource requested in this proposal is Ph.D. students, and therefore it is natural
that a large part of the impact should be directly related to them. Highly trained researchers
with well-developed practical and analytical skills are essential to maintining a competitive economy,
and through the experience of working on a wide range of materials and being exposed to
a broad base of expertise in condensed matter physics, alongside the formal training
they will be given, they will have a great opportunity to become a valuable and flexible
contribution to the people pipeline.

Impacts on the economy:
The impact of the research on the economy is likely to be in the much longer term. Commerical application
of high-temperature superconductivity is some way off, but a fundamental understanding of the normal
states of these materials is likely to be vital to future exploitation. Similarly, the quest for
highly spin-polarised materials is a central theme in technologies which take advantage of the electron's
spin as well as charge (so-called spintronics). Our contribution, originating from our previous success in
developing a new technique, will be in determining these spin-polarisations in a variety of promising
materials which could be commercially exploited in the futre.

Impacts on society:
Developments in condensed physics often find application in areas which have direct societal impact. Again, emphasising
the long term nature of any such realisation from the current proposal, developments in understanding of superconductivity
could lead, for example, to advances in magnet technology which could improve MRI scanners. Spintronics could
revolutionise data storage and processing, with impacts on consumer electronics and therefore quality of life.