Chang T.-YCheng C.-LHuang C.-CPeng C.-WHuang Y.-HChen T.-YLiu Y.-TCHI-FENG PAI2022-03-222022-03-22202124699950https://www.scopus.com/inward/record.uri?eid=2-s2.0-85111701068&doi=10.1103%2fPhysRevB.104.024432&partnerID=40&md5=0ad0f99a6baf7ed1b3125a79ba73e107https://scholars.lib.ntu.edu.tw/handle/123456789/598346A large unidirectional magnetoresistance (UMR) ratio of is found in W/CoFeB metallic bilayer heterostructures at room temperature. Three different regimes in terms of the current dependence of the UMR ratio are identified: a spin-dependent-scattering mechanism regime at small current densities (UMR ratio ), a spin-magnon-interaction mechanism regime at intermediate (UMR ratio ), and a spin transfer torque (STT) regime at (UMR ratio independent of J). We verify the direct correlation between this large UMR and the transfer of spin angular momentum from the W layer to the CoFeB layer by both field-dependent and current-dependent UMR characterizations. Numerical simulations further confirm that the large STT-UMR stems from the tilting of the magnetization affected by the spin Hall effect-induced STTs. An alternative approach to estimate dampinglike spin torque efficiencies from magnetic heterostructures is also proposed. ? 2021 American Physical SocietyCobalt compoundsIron compoundsMagnetoresistanceBi-layerCurrent dependenceMagnetic heterostructuresMagnon interactionsSpin angular momentumSpin dependent scatteringSpin transfer torqueSpin-torque efficiencySpin Hall effectjournal article10.1103/PhysRevB.104.0244322-s2.0-85111701068