Coexistence of unconventional spin Hall effect and antisymmetric planar Hall effect in IrO$_2$

TL;DR

This paper reports the simultaneous observation of unconventional spin Hall effect and antisymmetric planar Hall effect in IrO2 (111) films, revealing their dependence on crystal symmetry and providing insights into their physical origins.

Contribution

It demonstrates the coexistence of USHE and APHE in IrO2 (111) films and links their origins to the crystal symmetry, with improved spin torque efficiency.

Findings

USHE and APHE coexist in IrO2 (111) films.

Unconventional spin torque efficiency is more than doubled.

APHE arises from Lorentz force constrained by crystal symmetry.

Abstract

Crystal symmetry plays an important role in the Hall effects. Unconventional spin Hall effect (USHE), characterized by Dresselhaus and out-of-plane spins, has been observed in materials with low crystal symmetry. Recently, antisymmetric planar Hall effect (APHE) was discovered in rutile RuO2 and IrO2 (101) thin films, which also exhibit low crystal symmetry. In this study, we report the observation of both USHE and APHE in IrO2 (111) films, using spin-torque ferromagnetic resonance (ST-FMR) and harmonic Hall measurements, respectively. Notably, the unconventional spin torque efficiency from Dresselhaus spin was more than double that of a previous report. Additionally, the temperature dependence of APHE suggests that it arises from the Lorentz force, constrained by crystal symmetry. Symmetry analysis supports the coexistence of USHE and APHE and demonstrates that both originate from the crystal symmetry of IrO2 (111), paving the way for a deeper understanding of Hall effects and related physical phenomena.