Electrical measurement of the Spin Hall Effect isotropy in a ferromagnet

TL;DR

This study electrically measures the spin Hall effect anisotropy in ferromagnetic and paramagnetic phases of NiCu and NiPd, finding that ferromagnetic order does not significantly affect the effect's isotropy.

Contribution

It provides the first electrical measurements of spin Hall effect isotropy in ferromagnetic materials, demonstrating that ferromagnetic order does not induce notable anisotropy.

Findings

Ferromagnetic order does not cause significant spin Hall effect anisotropy.

Spin Hall effect remains roughly isotropic in ferromagnetic NiCu and NiPd.

Paramagnetic and ferromagnetic phases show similar spin charge interconversion properties.

Abstract

The spin-dependent transport properties of paramagnetic metals are roughly invariant under rotation. By contrast, in ferromagnetic materials the magnetization breaks the rotational symmetry, and thus the spin Hall effect is expected to become anisotropic. Here, using a specific design of lateral spin valves, we measure electrically the spin Hall Effect anisotropy in NiCu and NiPd, both in their ferromagnetic and paramagnetic phases. We show that the appearance of the ferromagnetic order does not lead to a sizeable anisotropy of the spin charge interconversion in these materials.