Reciprocity theorem in high-temperature superconductors

TL;DR

This paper investigates the validity of the reciprocity theorem in high-temperature superconductors, finding violations near the critical temperature and proposing anisotropy and vortex dynamics as possible explanations.

Contribution

It provides experimental evidence of reciprocity theorem violation in HTSC and suggests new theoretical considerations involving anisotropy and vortex behavior.

Findings

Reciprocity theorem is not valid near critical temperature in HTSC.

Violation linked to anisotropy and vortex-antivortex dynamics.

Spontaneous magnetization suggests possible symmetry breaking.

Abstract

This article is devoted to the problem of the validity of the reciprocity theorem in high-temperature superconductors (HTSC). The violation of the reciprocity theorem in zero external magnetic fields has been studied. Experimental data obtained for two different superconducting materials: BiSrCaCuO and YBaCuO are presented. Results show that the basic form of the reciprocity theorem (without consideration of any additional anisotropy) is not valid near the critical temperature. We assume that the reciprocity theorem breaking is connected with the existence of an extraordinary transverse electric field originated from additional anisotropy and more general form of the reciprocity relations should be valid. However, the origin of this anisotropy is not clear yet. We suggest that the vortex-antivortex dynamics model taking into account vortex guiding can be responsible for the observed effect. Also the explanation based on weak P and T symmetry breaking in HTSC which is supported by the observation of the spontaneous magnetisation can not be excluded.