Anomalous Hall effect in the half-metallic Heusler compound Co₂TiX (X=Si, Ge)

Abstract

Though Weyl fermions have recently been observed in several materials with broken inversion symmetry, there are very few examples of such systems with broken time reversal symmetry. Various Co2-based half-metallic ferromagnetic Heusler compounds are lately predicted to host Weyl-type excitations in their band structure. These magnetic Heusler compounds with broken time reversal symmetry are expected to show a large momentum space Berry curvature, which introduces several exotic magnetotransport properties. In this paper, we present a systematic analysis of experimental results on the anomalous Hall effect (AHE) in Co2TiX (X=Si and Ge). This study is an attempt to understand the role of Berry curvature on AHE in the Co2TiX family of materials. Anomalous Hall resistivity is observed to scale quadratically with longitudinal resistivity for both compounds. The detailed analysis indicates that in anomalous Hall conductivity, the intrinsic Karplus-Luttinger Berry phase mechanism dominates over the extrinsic skew scattering and side-jump mechanism.