Electrically controllable superconducting memory effect in UTe2.

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 phases4,5. 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 phases9,10, we find that direct current pulses can push the material in and out of a metastable state that has an enhanced critical current density Jc. This switching is controllable by the strength and duration of the stimuli, with the system 'remembering' whether it is in the high or low Jc 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 Jc. 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 interfaces11-14, 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.