Sign Change of the Flux Flow Hall Effect in HTSC

TL;DR

This paper proposes a new mechanism explaining the sign change of the Hall effect in high-temperature superconductors' flux flow region, based on differences in electron density inside and outside vortex cores, especially in dirty samples.

Contribution

It introduces a novel theoretical explanation for the Hall effect sign change involving vortex core electron density differences, applicable in dirty superconductor conditions.

Findings

The sign change can occur due to vortex core electron density differences.

Double sign change possible as a function of temperature.

Mechanism is significant in dirty superconductor regimes.

Abstract

A novel mechanism for the sign change of the Hall effect in the flux flow region is proposed. The difference $\delta n $ between the electron density at the center of the vortex core and that far outside the vortex causes the additional contribution to the Hall conductivity $\delta\sigma_{xy}=-\delta n ec/B$. This contribution can be larger than the conventional one in the dirty case $\Delta(T)\tau <1$. If the carrier density inside the core exceeds that far outside, a double sign change may occur as a function of temperature.