In this PhD project, we intend to probe two well-known unconventional superconductors with thermal transport, through an original approach combining macroscopic and microscopic probes. These superconductors are UPt3 and UTe2, chosen because they address two issues currently under hot debate in the international community, that could strongly benefit from this new approach. UPt3 addresses the question of topological superconductivity, while UTe2 requires a clear identification of its spin-triplet superconducting order parameter.
Topological superconductivity is an active subject on the theoretical side and because of its potential interest in the field of quantum engineering. However, unambiguous experimental results are scarce, and we intend to focus here on UPt3, the first ever superconductor demonstrating the existence of transitions between superconducting phases, together with convincing evidences for chiral superconductivity. The goal is to probe predictions on the existence of an anomalous (zero field) thermal Hall effect, which would arise from the chiral edge currents.
A new approach is proposed, combining a newly designed set-up for the macroscopic measurement of thermal conductivity and thermal Hall effect, together with a microscopic probe realizing Scanning Thermal Spectroscopy. This will be realized thanks to a collaboration between two labratories in Grenoble: a team Pheliqs, mastering high quality crystal growth of these systems together with low temperature thermal transport measurements, and two teams in Néel, experts in Scanning SQUID microscopy and microscopic thermal measurements down to sub-Kelvin temperatures.
With this project, the PhD student will acquire very broad skills, ranging from sample preparation, low temperature instrumentation, and major actual issues in the field of quantum materials.