Anomalous Hall Effect in Variable Range Hopping Regime: Unusual Scaling Law and Sign Reversal with Temperature

TL;DR

This paper investigates the anomalous Hall effect in variable-range-hopping regimes, revealing unusual scaling laws and temperature-dependent sign reversal, which deepen understanding of topological properties in magnetic materials.

Contribution

It presents the first experimental study of AHE in VRH regimes, discovering unique scaling behaviors and temperature-induced sign changes not previously reported.

Findings

Unusual scaling law of AHE coefficient with exponent > 2

Sign reversal of AHE coefficient with temperature

Contrasting behavior between AHE and OHE in VRH regimes

Abstract

Anomalous Hall effect (AHE) is important for understanding the topological properties of electronic states, and provides insight into the spin-polarized carriers of magnetic materials. AHE has been extensively studied in metallic, but not variable-range-hopping (VRH), regime. Here we report the experiments of both anomalous and ordinary Hall effect (OHE) in Mott and Efros VRH regimes. We found unusual scaling law of the AHE coefficient $Rah=aRxx^b$ with b>2, contrasting the OHE coefficient $Roh=cRxx^d$ with d<1. More strikingly, the sign of AHE coefficient changes with temperature with specific electron densities.