Ephemeral Superconductivity Atop the False Vacuum

TL;DR

This paper explores transient superconductivity that occurs temporarily at the boundary of a false vacuum state in graphene multilayers, proposing a detection method and demonstrating its relevance in rhombohedral graphene.

Contribution

It introduces the concept of ephemeral superconductivity at false vacuum boundaries and demonstrates its potential in graphene systems, highlighting a new way to study non-equilibrium superconductivity.

Findings

Transient superconductivity can be induced and detected via transport measurements.

False vacuum states can have significantly extended lifetimes due to superconductivity.

Superconductivity can temporarily enhance the stability of false vacuum states.

Abstract

A many body system in the vicinity of a first-order phase transition may get trapped in a local minimum of the free energy landscape. These so-called false-vacuum states may survive for exceedingly long times if the barrier for their decay is high enough. The rich phase diagram obtained in graphene multilayer devices presents a unique opportunity to explore transient superconductivity on top of a correlated false vacuum. Specifically, we consider superconductors which are terminated by an apparent first-order phase transition to a correlated phase with different symmetry. We propose that quenching across this transition leads to a non-equilibrium ephemeral superconductor, readily detectable using straightforward transport measurements. Besides enabling a simple detection scheme, the transient superconductor also generically enhances the false vacuum lifetime, potentially by orders of magnitude. In several scenarios, the complimentary effect takes place as well: superconductivity is temporarily emboldened in the false vacuum, albeit ultimately decaying. We demonstrate the applicability of these claims for two different instances of superconductivity terminated by a first order transition in rhombohedral graphene. The obtained decay timescales position this class of materials as a promising playground to unambiguously realize and measure non-equilibrium superconductivity.