We are happy to consider applications for both PhD and for self-funded MSc by Research applicants all year round.
Research leading to the degree of PhD or an MSc by Research at the University of Bristol may be undertaken under the direction of an academic within the group.
If you have an idea for a research project/topic please apply and your application and research interests will be considered. For information about becoming a PhD student with us, see postgraduate study.
Superconductivity with time-reversal symmetry breaking Cooper pairing states
[Supervisor: James Annett]
There are now a number of experiments showing unusual changes in the magnetic properties of some materials at the temperature when they become superconducting. These imply that the superconducting state of the material has time reversal symmetry breaking (TRSB) at the critical temperature, Tc. This can be the case if the Cooper pairs are intrinsically magnetic, for example having pairing states with intrinsic spin or orbital angular momentum. Such states are theoretically possible, and there is strong evidence that this may occur in a few rare materials, such as Sr2RuO4.
In this project we will investigate a new group of materials in which this TRSB has recently been detected in muon-spin-rotation(mu-SR) experiments as the ISIS facility at STFC Rutherford Laboratory. So far the materials where this have been found include LaNiC2, LaNiGa2 and Re6Zr. Working in partnership with a collaborating theory group led by Dr Jorge Quintanilla at the University of Kent this PhDproject supervised by Prof James Annett will investigate in detail the possible pairing states in these materials. The work will involve both ab initio electronic structure calculation as well as developing theoretical quantum many-body models of the possible pairing mechanisms which may explain these exciting and novel experimental results.
- Kerr rotation in the unconventional superconductor Sr2RuO4, M. Gradhand, K. I. Wysokinski, J.F. Annett, J.F. & B.L. Györffy, Physical Review B. 88, 094504 (2013).
- Relativistic analysis of the pairing symmetry of the noncentrosymmetric superconductor LaNiC2, J Quintanilla, A.D. Hillier, J.F. Annett and R Cywinski, Physical Review B. 82, p. 174511 (2010).
- Nonunitary Triplet Pairing in the Centrosymmetric Superconductor LaNiGa2,Phys. Rev. Lett. 109, 097001 (2012).
- Detection of Time-Reversal Symmetry Breaking in the Noncentrosymmetric Superconductor Re6Zr Using Muon-Spin Spectroscopy
- R.P. Singh, A.D. Hillier, B. Mazidian, J. Quintanilla, J.F. Annett, M. Lees, D. McK. Paul, D. & G. Balakrishnan, Physical Review Letters, 112, 107002 (2014).
Who to contact
If you are interested in any of our postgraduate opportunities, contact Martin Gradhand.