Anomalous anisotropy of spin current in a cubic spin source with noncollinear antiferromagnetism

TL;DR

This paper reports an unexpected anisotropy in spin current in cubic Mn${_3}$Pt films, arising from intertwined spin Hall effects, enabling novel low-power spintronic applications.

Contribution

It reveals the anomalous anisotropy of spin current in a cubic noncollinear antiferromagnet, supported by symmetry analysis and experimental spin torque measurements.

Findings

Spin current anisotropy depends on current direction in Mn${_3}$Pt (001)

The anisotropy originates from intertwined T-odd and T-even spin Hall effects

Potential for low-power, field-free magnetization switching in spintronics

Abstract

Cubic materials host high crystal symmetry and hence are not expected to support anisotropy in transport phenomena. In contrast to this common expectation, here we report an anomalous anisotropy of spin current can emerge in the (001) film of Mn${_3}$Pt, a noncollinear antiferromagnetic spin source with face-centered cubic structure. Such spin current anisotropy originates from the intertwined time reversal-odd ($T$-odd) and time reversal-even ($T$-even) spin Hall effects. Based on symmetry analyses and experimental characterizations of the current-induced spin torques in Mn${_3}$Pt-based heterostructures, we find that the spin current generated by Mn${_3}$Pt (001) exhibits exotic dependences on the current direction for all the spin components, deviating from that in conventional cubic systems. We also demonstrate that such an anisotropic spin current can be used to realize low-power spintronic applications such as the efficient field-free switching of the perpendicular magnetizations.