Spin Hall Magnetoresistance and Spin-Orbit Torque Efficiency in Pt/FeCoB Bilayers

The spin Hall magnetoresistance (SMR) of Pt/FeCoB bilayers with in-plane magnetocrystalline anisotropy was analyzed with respect to a second-order effect in the sensing current, which acts, through the spin Hall effect in Pt, as a torque on the magnetization of the ferromagnetic (FM) layer and changes slightly its configuration. This leads to a small current-dependent shift of the SMR curves in field that allows, in structures with a multidomain state (e.g., Hall bars), the determination of the sign of the magnetic remanence. The SMR measurements were performed as a function of the Pt thickness and the spin Hall angle, and the diffusion length and the field-like and damping-like spin-orbit-torque (SOT) efficiency were determined. The results were compared with the values obtained from harmonic Hall voltage and SOT-FM resonance (FMR) measurements and show a good agreement.