PhD projects 2018

Projects available in our group for 2018 are listed below. Please get in touch with Dr Amalia Coldea (amalia.coldea@physics.ox.ac.uk) for further details.
We welcome applications from enthusiastic students who are excited and challenged by understanding the rich novel physical phenomena found in novel electronic materials.

1. Electronic structure of iron-based superconductors using high magnetic fields

This project is focus on understanding electronic behaviour of novel superconducting single crystals by using advanced techniques such a quantum oscillations detected by magnetotransport or torque magnetometry detected in high magnetic fields and at very low temperature in high quality single crystals. These studies will be complemented by angle resolved photoemission spectroscopy and first-principle calculations to understand all the relevant details of the Fermi surface of superconducting single crystals. Experiments will be performed both in Oxford and at international high magnetic field facilities.

2. Revealing topological signatures and the electronic behaviour of bulk quantum materials with Dirac dispersion

This is mainly an experimental project combining electronic transport and quantum oscillations to detect unusual signatures of the manifestation of topology in single crystals of quantum materials with Dirac dispersions. The student will perform a series of studies in high magnetic fields and at low temperatures to search for evidence of non-trivial Berry phases and low temperature quantum transport. Studies will be also extended under applied pressure to identify proximity to new toplogical superconducting phase. The work will be combined with first-principle band structure calculations to compare with experiments and disentangle trivial from non-trivial effects.

3. Tuning electronic structure of iron-based superconductors with applied strain and external pressure

A nematic state is a form of electronic order which breaks the rotational symmetries without changing the translational symmetry of the lattice, and this state may play an important role in understanding high temperature superconductivity. A clear manifestation of a nematic Fermi surface is its strong in-plane anisotropy in transport properties and sensitivity to external parameters, in particular in-plane strain. The resistivity anisotropy is determined by both the electronic structure and the scattering, and the expected Fermi surface deformation give rise naturally to anisotropic electronic properties, whereas the spin-nematic ordering leads to an anisotropy of the electron scattering. This project will consist in magnetotransport studies under strain and pressure to understand the nematic and superconducting states of iron-based superconductors.

4. Developing electronic tunable devices of thin flakes of iron-based superconductors and Dirac materials

This project is to explore electronic and topological behaviour of quasi-two dimensional devices based on thin flakes of highly crystalline superconducting iron-based chalcogenides as well as Dirac and Weyl semimetals. The project will involve device preparation and a suite of physical properties measurements to study their electronic properties using high magnetic field and low temperatures. The aim is to search for quantum phenomena as well as for signature of topological matter in these highly tunable quantum material devices.

5. Projects on Applied Superconductivity

Novel Superconductors for Practical Applications

Superconductors are wonder materials with a large range of practical applications. Among them, their ability to carry current without resistance makes them suitable for applications in energy transfer and storage. Furthermore, superconductors can be used for building and testing highly sensitive quantum devices and they can be found in high speed levitating trains and in superconducting magnets, as those in MRI scanners. This project is to understand the fundamental and the practical limitations of new superconducting materials and the effect of extreme conditions on their superconducting properties. The project will be hosted by the recently funded
Oxford Centre for Applied Superconductivity (CfAS) in the Department of Physics. The student will investigate the phase diagrams of novel superconducting system in different forms from single crystals, thin films, wires and tapes under different extreme conditions of high magnetic field, strain and pressure. Experiments using advanced techniques for transport and thermodynamic measurements will be performed using high magnetic field facilities available in Oxford and elsewhere. The experimental data will be complemented by theoretical modelling and further development of advanced experimental techniques may be required during the project.

Details about the application process can be found here and concerning the available scholarships can be found here.