Atomic disorder and Berry phase driven anomalous Hall effect in a Co2FeAl Heusler compound

Abstract

Co 2 -based Heusler compounds are promising materials for spintronics applications due to their high Curie temperature, large spin polarization, large magnetization density, and exotic transport properties. In the present paper, we report the anomalous Hall effect (AHE) in a polycrystalline Co 2 FeAl Heusler compound using combined experimental and theoretical studies. The Rietveld analysis of high-resolution synchrotron x-ray diffraction data reveals a large degree (∼50%) of antisite disorder between Fe and Al atoms. The analysis of anomalous transport data provides the experimental anomalous Hall conductivity (AHC) about 227 S/cm at 2 K with an intrinsic contribution of 155 S/cm, which has nearly constant variation with temperature. The detailed scaling analysis of anomalous Hall resistivity suggests that the AHE in Co 2 FeAl is governed by the Berry phase driven intrinsic mechanism. Our theoretical calculations reveal that the disorder present in the Co 2 FeAl compound enhances the Berry curvature induced intrinsic AHC.

Existence of complex magnetic ground state and topological Hall effect in centrosymmetric silicide DyScSi

“…In ferromagnets, anomalous Hall effect (AHE), which arises due to spin-orbit coupling, is observed [8]. This type of effect has been observed in intermetallic like Co 2 FeSi [9], Fe 3 Ge [10], Co 2 FeAl [11]. Apart from this, an additional contribution to ρ xy known as topological Hall effect (THE) is recently reported in some systems.…”

Intrinsic anomalous Hall conductivity and real space Berry curvature induced topological Hall effect in Ni2MnGa magnetic shape memory alloy

“…To get more insight about the origin of AHE, it is necessary to look at the behavior of anomalous Hall conductivity (AHC) with temperature. In order to obtain that, first of all, Hall conductivity was calculated using the tensor relation given below [16,83],…”

“…The Berry curvature acts like a pseudomagnetic field in the momentum space, due to which the conducting electrons gain an anomalous velocity perpendicular to the electric field, thus resulting in the AHE even in the absence of an external magnetic field [15]. Since the discovery of the concept of the Berry curvature, which preserves its topology, the AHE has received vast interest in topological materials [4,11,16]. A finite Berry curvature manifests a nonzero AHE, and for a finite Berry curvature, the space inversion symmetry or time reversal symmetry must be broken in a material [1,11].…”