The low-frequency response in the surface superconducting state of ZrB$_{12}$ single crystal}

TL;DR

This paper investigates the nonlinear low-frequency electromagnetic response of ZrB$_{12}$ single crystals in the surface superconducting state, revealing how transitions between metastable states under ac fields influence the dynamics.

Contribution

It provides a detailed analysis combining experimental measurements, numerical solutions of Ginzburg-Landau equations, and phenomenological models to understand surface superconducting state dynamics.

Findings

Low-frequency response is governed by transitions between metastable states.

Relaxation rate of the system was quantitatively determined.

Surface superconducting states exhibit characteristic nonlinear behavior.

Abstract

The large nonlinear response of a single crystal ZrB$_{12}$ to an ac field (frequency 40 - 2500 Hz) for $H_0>H_{c2}$ has been observed. Direct measurements of the ac wave form and the exact numerical solution of the Ginzburg-Landau equations, as well as phenomenological relaxation equation, permit the study of the surface superconducting states dynamics. It is shown, that the low frequency response is defined by transitions between the metastable superconducting states under the action of an ac field. The relaxation rate which determines such transitions dynamics, is found.