Postgraduate Scholarship in Complex Quantum Order in Unconventional Superconductors

A funded PhD position is available in the field of Condensed Matter Theory under the supervision of Dr J Quintanilla. Deadline Date for Applications: 22 June 2018. Details of the research project, eligibility criteria, funding available and how to apply can be found here.


Time-reversal symmetry breaking in superconductors through loop Josephson-current order

Sudeep Kumar Ghosh, James F. Annett, Jorge Quintanilla

arXiv:1803.02618 [cond-mat.supr-con]

(Submitted on 7 Mar 2018)

We propose a superconducting instability where loop Josephson-currents form spontaneously within a unit cell at the critical temperature, Tc. Such currents break time-reversal symmetry (TRS) without needing an unconventional pairing mechanism. Using Ginzburg-Landau theory we show how they emerge in a toy model and estimate the size of the resulting magnetization, which is consistent with recent muon-spin relaxation experiments. We discuss the crystal symmetry requirements and show that they are met by the Re6X (X=Zr, Hf, Ti) family of TRS-breaking, but otherwise seemingly conventional, superconductors.


First Paper from EPSRC-funded Project

The first paper resulting from our collaboration since the start of joint EPSRC funding for our project has now been published:

P. Whittlesea, J. Quintanilla, J. F. Annett, A. D. Hillier & C. Hooley. Can Topological Transitions be Exploited to Engineer Intrinsically Quench-Resistant Wires? IEEE Transactions on Applied Superconductivity 28, 1–5 (2018). DOI: 10.1109/TASC.2018.2791515

This is also our first paper in IEEE Transactions, in line with our aim to enhance communication between fundamental and applied superconductivity research. The paper explores a novel application of topological transitions, namely quench prevention – see this earlier post for further explanations and a link to some animations. The work also involved Chris Hooley of the University of St Andrews.


Engineering Quench Resilience via Topological Transitions: a Proposal

We are presenting a poster at the European Conference on Applied Superconductivity on Thursday. It presents work carried out by members of the USC collaboration at Kent,  Bristol and RAL in collaboration also with Chris Hooley (St Andrews). In it we propose that chemically-tuning certain superconductors to a topological transition state may help make them more resilient to quenches. This may be the first proposal of an application of topological transitions outside the field on quantum information processing. One of the aims of our collaboration is to help bridge the gap between fundamental research in superconductivity and its applications.

Follow this link for a PDF of the poster and supplemental material (animations).

Two PDRA’s now in post

With the arrival of Sudeep K. Ghosh, who took up post as a PDRA in the University of Kent yesterday, and Gabor Csire, who joined Bristol in a similar capacity recently, our tem is now fully assembled and already working hard at solving some of the most intriguing puzzles in superconductivity research.


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