Extrinsic Anomalous Hall effect in Mn Doped GeSnTe Semiconductors in the Bad Metal Hopping Regime

TL;DR

This study investigates the extrinsic anomalous Hall effect in Mn-doped GeSnTe semiconductors, revealing complex scattering mechanisms, polaronic effects, and a universal conductivity scaling law in the bad metal hopping regime.

Contribution

It provides new insights into the extrinsic scattering mechanisms and scaling behavior of the anomalous Hall effect in Mn-doped GeSnTe in the bad metal regime.

Findings

Observation of anomalous Hall effect dominated by side jump scattering

Identification of universal scaling law σxy ~ σxx^1.6 in low conductivity regime

Detection of polaronic effects influencing carrier mobility

Abstract

We present high field magnetotransport studies of Ge1-x-y(SnxMny)Te bulk multiferroics with diamagnetic Sn and paramagnetic Mn concentration x = 0.38 to 0.79 and y = 0.02 to 0.086, respectively. The zero field resistivity, {\rho}(T) takes significant contribution from defects below T = 20 K however, a mixed scattering contribution from dynamic disorder and unusual sources is estimated from T = 20 K to 300 K. The carrier mobility shows anomalous temperature dependence from T0.2 to T0.5 which hints towards possible presence of polaronic effects resulting from coupling of holes with phonons. This anomalous behavior cannot be understood in terms of pure phononic scattering mechanism at high temperature. From point of view of high field results, the transverse component of magnetoresistivity manifests anomalous Hall effect originating from extrinsic scattering sources, particularly the side jump mechanism reveals a larger contribution. We also find that the correlation between the transverse and longitudinal conductivities follow the universal scaling law {\sigma}xy ~ {\sigma}xxn where n = 1.6 in the low conductivity limit. The values n = 1.5 to 1.8 obtained for the present GSMT alloys justify the bad metal hopping regime since the results fall in the low conductivity ferromagnetic family with {\sigma}xx ~ 104 ohmcm-1. The interpretation of the n = 1.6 scaling in the low conductivity regime is thus far not fully understood. However, the anomalous Hall resistivity scaling with modified relation by Tian et al is indicative of the dominant side jump scattering along with noticeable role of skew scattering.