Electrically controllable superconducting memory effect in UTe₂.

Abstract

Multiphase superconductors-materials that host two or more distinct superconductive phases-are exceptionally rare. Examples include heavy-fermion CeRh₂As₂ alongside some uranium compounds such as UPt₃ and URhGe (refs. ^1,2,3). In the multiphase p-wave superfluid ³He, complex vortex dynamics can occur at the phase boundary between the A and B phases^4,5. Here we study the p-wave superconductor candidate UTe₂ (refs. ^6-8). On applying a magnetic field to access an intermediate regime straddling two distinct superconducting phases^9,10, we find that direct current pulses can push the material in and out of a metastable state that has an enhanced critical current density J_c. This switching is controllable by the strength and duration of the stimuli, with the system 'remembering' whether it is in the high or low J_c state for extended periods. We interpret this phenomenology to be due to the quenching of a disordered out-of-equilibrium glassy vortex state under perturbation, which has stronger pinning forces and thus higher J_c. The equilibrium vortex lattice is reattained by annealing the system with a gradual current ramp, returning it to the original state. Rather than requiring proximate magnetic or semiconducting interfaces^11-14, this memory functionality seems to be an intrinsic property of UTe₂ rooted in the superconducting order itself. Our findings underscore the rich complexity of multiphase quantum vortex matter.