Large out-of-plane spin-orbit torque in topological Weyl semimetal TaIrTe₄.

Abstract

The unique electronic properties of topological quantum materials, such as protected surface states and exotic quasiparticles, can provide an out-of-plane spin-polarized current needed for external field-free magnetization switching of magnets with perpendicular magnetic anisotropy. Conventional spin-orbit torque (SOT) materials provide only an in-plane spin-polarized current, and recently explored materials with lower crystal symmetries provide very low out-of-plane spin-polarized current components, which are not suitable for energy-efficient SOT applications. Here, we demonstrate a large out-of-plane damping-like SOT at room temperature using the topological Weyl semimetal candidate TaIrTe₄ with a lower crystal symmetry. We performed spin-torque ferromagnetic resonance (STFMR) and second harmonic Hall measurements on devices based on TaIrTe₄/Ni₈₀Fe₂₀ heterostructures and observed a large out-of-plane damping-like SOT efficiency. The out-of-plane spin Hall conductivity is estimated to be (4.05 ± 0.23)×10⁴ (ℏ ⁄ 2e) (Ωm)^-1, which is an order of magnitude higher than the reported values in other materials.