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Correction of out-of-plane spin torque extracted from second harmonic Hall measurements: Role of antisymmetric planar Hall effects
Phys. Rev. B 112, 174409 – Published 10 November, 2025
DOI: https://doi.org/10.1103/b64t-dcvz
Abstract
Materials with broken in-plane mirror symmetry can generate spin current with out-of-plane spin polarization (Z spins), enabling field-free spin-orbit torque (SOT) switching. The second harmonic Hall (SHH) technique is widely used to quantify this spin component electrically. However, these materials often exhibit an antisymmetric planar Hall effect (APHE), which is typically neglected in conventional SHH analysis models. Using rutile (101) as a model system, we demonstrate that APHE introduces a non-negligible artifact in the SHH signal, leading to a torque extraction error of up to 20% in the dampinglike z component. This deviation, captured by an analytical model, scales with the APHE-to-PHE ratio and the amplitude of in-plane spin components (X and Y spins). Our results underscore the importance of accounting for APHE when evaluating out-of-plane SOT components via SHH, particularly in low-symmetry systems.
