The physics of vortices in the high temperature superconductors continues to attract attention, and is of theoretical and technological interest. Their complex defect structures influence the different vortex phases, and it remains an experimental challenge to correlate structural observations with those of magnetization. The project will study thermally activated and quantum creep, focusing on different structural influences. A newly developed high-precision torque magnetometer will be utilised, while structural characterisation will be undertaken with CEA Saclay. Quantum creep will be studied as a function of field and defects in heavy ion irradiated single crystals. Different types of pinning will also be investigated in chemically doped samples.
The high-field quantum creep regime will be investigated, in organic superconductors, to distinguish between "bundle flow" and "plastic flow" The vortex dynamics of heavy fermion superconductors, which have transitions below 1K, have never been carefully investigated, and the project will be extended to these.
The project will provide an important link between structure, the pinning, and the vortex dynamics in the quantum regime, and extend the range of this new field of physics.
Training content (objective, benefit and expected impact)
The training will be in torque and magnetisation techniques, as well as furthering my already comsiderable experience of structural studies, equiping me with a rare combination of skills in two powerfully complementary areas.