Local bistability under microwave heating for spatially mapping disordered superconductors

TL;DR

This paper presents a theoretical study of microwave-induced bistability in disordered superconductors, proposing a method to locally map inhomogeneous superfluid flow with high spatial resolution using a sharp domain wall.

Contribution

It introduces a novel theoretical framework for local bistability in disordered superconductors under microwave heating, enabling high-resolution spatial mapping.

Findings

Bistability leads to a stable normal region with a sharp domain wall.

Microwave heating can induce submicrometer-sized normal regions.

Proposed method enhances spatial resolution for mapping superfluid flow.

Abstract

We theoretically study a strongly disordered superconducting layer heated by near-field microwave radiation from a nanometric metallic tip. The microwaves heat up the quasiparticles, which cool by phonon emission and conduction away from the heated area. Due to a bistability with two stable states of the electron temperature under the tip, the heating can be tuned to induce a submicrometer-sized normal region bounded by a sharp domain wall between high- and low-temperature states. We propose this as a local probe to access different physics from existing methods, for example, to map out inhomogeneous superfluid flow in the layer. The bistability-induced domain wall can significantly improve its spatial resolution.