High spin polarization of the anomalous Hall current in Co-based Heusler compounds

TL;DR

This study predicts that certain Co-based Heusler compounds exhibit nearly fully spin-polarized anomalous Hall currents with potential applications in spintronics, despite not being half-metallic.

Contribution

First principles calculations reveal that many Co-based Heusler compounds can act as anomalous Hall half-metals, expanding their potential in spintronic devices.

Findings

Charge Hall current in these compounds is nearly fully spin-polarized.

The spin current to charge current ratio exceeds 1.0.

Compounds like Co2MnAl, Co2MnGa, and Co2MnIn have large anomalous and spin Hall conductivities.

Abstract

Based on first principles density functional calculations of the intrinsic anomalous and spin Hall conductivities, we predict that the charge Hall current in Co-based full Heusler compounds Co$_2$XZ (X = Cr and Mn; Z = Al, Si, Ga, Ge, In and Sn) except Co$_2$CrGa would be almost fully spin-polarized even although Co$_2$MnAl, Co$_2$MnGa, Co$_2$MnIn and Co$_2$MnSn do not have a half-metallic band structure. Furthermore, the ratio of the associated spin current to the charge Hall current is slightly larger than 1.0. This suggests that these Co-based Heusler compounds, especially Co$_2$MnAl, Co$_2$MnGa and Co$_2$MnIn which are found to have large anomalous and spin Hall conductivities, might be called anomalous Hall half-metals and could have valuable applications in spintronics such as spin valves as well as magnetoresistive and spin-torque driven nanodevices. These interesting findings are discussed in terms of the calculated electronic band structures, magnetic moments and also anomalous and spin Hall conductivities as a function of the Fermi level.