Vortex configurations and metastability in mesoscopic superconductors

TL;DR

This paper investigates vortex behavior and metastability in mesoscopic superconductors with rectangular cross sections, combining analytical calculations and simulations to reveal complex magnetization phenomena including hysteresis and vortex chain formation.

Contribution

It provides analytical expressions for flux distribution and energy barriers, and introduces a Langevin simulation approach to study vortex dynamics and metastable states in mesoscopic superconductors.

Findings

Hysteretic magnetization curves with vortex entry and exit peaks

Paramagnetic response observed in part of the magnetization cycle

Vortices form parallel chains in elongated rectangles

Abstract

The vortex dynamics in mesoscopic superconducting cylinders with rectangular cross section under an axially applied magnetic field is investigated in the multivortex London regime. The rectangles considered range from a square up to an infinite slab. The flux distribution and total flux carried by a vortex placed in an arbitrary position of the sample is calculated analytically by assuming Clem's solution for the vortex core. The Bean-Livingston energy barrier is also analytically calculated in this framework. A Langevin algorithm simulates the flux penetration and dynamical evolution of the vortices as the external field is slowly cycled. The simulated magnetization process is governed by metastable states. The magnetization curves are hysteretic, with paramagnetic response in part of the downward branch, and present a series of peaks corresponding to the entry or expulsion of a single vortex. For elongated rectangles, the vortices arrange themselves into parallel vortex chains and an additional modulation of the magnetization, corresponding to creation or destruction of a vortex chain, comes out.