Uniaxial pressure can dramatically alter the electronic properties of materials, by directly driving anisotropic changes in the nearest-neighbor overlap integrals between atomic sties. It typically drives much larger changes to the electronic structure of materials than equal hydrostatic pressures. Uniaxial pressure can also reversibly and precisely lift lattice symmetries; symmetry is a basic paradigm for analysis of problems in solid state physics, and controllably breaking symmetries is a powerful probe of novel forms of order in correlated electron systems, for example superconductivity and density wave orders.
We have recently developed new apparatus, based on piezoelectric stacks, for applying and tuning uniaxial pressure, and plan a major research effort extending development of this technique and applying it to new materials. In this project, you will help implement this technique within angle-resolved photoemission (ARPES), a vital tool for studying the electronic structure of materials. and lead measurements both using the state-of-the-art ARPES system in St Andrews, and at synchrotron light sources in the UK, Europe, and the USA. You will also perform low-temperature transport and magnetic susceptibility measurements as a function of uniaxial strain using custom apparatus at the MPI-CPfS. There may be further opportunities for designing new apparatus and techniques, for example uniaxial pressure apparatus suitable for ARPES, scanning probe microscopes, and new sample preparation and mounting techniques that allow higher strains and greater precision.
Essential qualifications for this project are a curiosity about basic science, an interest in practical engineering problems, and a willingness to travel.