Quantum depinning of a pancake-vortex from a columnar defect

TL;DR

This paper investigates the quantum and thermal depinning of pancake vortices from columnar defects in superconductors, providing a universal Euclidean action calculation and analyzing the quantum-classical transition.

Contribution

It introduces a universal calculation of the Euclidean action for vortex depinning across all temperatures, independent of the pinning potential details.

Findings

Transition from quantum to classical depinning is second-order with temperature scaling as F^{4/3}

Euclidean action is universal and does not depend on the pinning potential form

Large vortex mass effects are discussed in the superclean limit

Abstract

We consider the problem of the depinning of a weakly driven ($F\ll F_{c}$) pancake vortex from a columnar defect in a Josephson-coupled superconductor, where $F$ denotes the force acting on the vortex ($F_{c}$ is the critical force). The dynamics of the vortex is supposed to be of the Hall type. The Euclidean action $S_{Eucl}(T)$ is calculated in the entire temperature range; the result is universal and does not depend on the detailed form of the pinning potential. We show that the transition from quantum to classical behavior is second-order like with the temperature $T_{c}$ of the transition scaling like $F^{{4}/{3}}.$ Special attention is paid to the regime of applicability of our results, in particular, the influence of the large vortex mass appearing in the superclean limit is discussed.