Numerical study of the strongly screened vortex glass model in an external field

TL;DR

This study investigates the vortex glass model in high-temperature superconductors under strong screening and external magnetic fields, revealing that the vortex configuration is highly sensitive to field variations and that true superconductivity is absent at finite temperatures.

Contribution

The paper provides exact ground state calculations showing the sensitivity of vortex configurations to external fields and the independence of excitation loop energies from the field in the strong screening limit.

Findings

Vortex configurations vary drastically with infinitesimal field changes.

Excitation loop energies are independent of the external field.

No true superconducting state exists at finite temperatures regardless of the external field.

Abstract

The vortex glass model for a disordered high-T_c superconductor in an external magnetic field is studied in the strong screening limit. With exact ground state (i.e. T=0) calculations we show that 1) the ground state of the vortex configuration varies drastically with infinitesimal variations of the strength of the external field, 2) the minimum energy of global excitation loops of length scale L do not depend on the strength of the external field, however 3) the excitation loops themself depend sensibly on the field. From 2) we infer the absence of a true superconducting state at any finite temperature independent of the external field.