YbRh2Si2 is a canonical heavy fermion metal with a field tuned quantum critical point. In recent work we have developed transport measurements on high quality single crystal samples which show it to be a superconductor below 10 mK. We have also determined the phase diagram in a magnetic field.
This new superconductor has numerous interesting features, and is a candidate for spin-triplet topological superconductivity.
There is an interplay between coexisting, possibly intertwined, magnetism and superconductivity, with nuclear magnetism playing a role. The onset of superconductivity is anisotropic, and there is evidence for multiple superconducting phases.
The target of this project is to firmly identify the nature of the superconducting order in this system, and to exploit it in devices. This will involve: transport measurements in samples micro-structured by focussed ion beam (FIB); the development of new techniques for measurements into the microkelvin regime; exploitation of via nuclear magnetism (through by Yb isotope enrichment), strain, magnetic field and temperature.
This project is based in the London Low Temperature Laboratory, Royal Holloway, which is part of the European Microkelvin Platform.
Collaborators: Max Planck Institute for Chemical Physics of Solids, Dresden, Germany. Physics Insitute, Goethe University, Frankfurt, Germany PTB, Berlin