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arXiv · 2105.02787

Interfacial and bulk spin Hall contributions to field-like spin-orbit torque generated by Iridium

Sutapa Dutta·Arnab Bose·A. A. Tulapurkar·R. A. Buhrman·D. C. Ralph
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Abstract

We present measurements of spin orbit torques generated by Ir as a function of film thickness in sputtered Ir/CoFeB and Ir/Co samples. We find that Ir provides a damping-like component of spin orbit torque with a maximum spin torque conductivity 1.4e5 in SI unit and a maximum spin-torque efficiency of 0.04, which is sufficient to drive switching in an 0.8 nm film of CoFeB with perpendicular magnetic anisotropy. We also observe a surprisingly large field like spin orbit torque. Measurements as a function of Ir thickness indicate a substantial contribution to the FLT from an interface mechanism so that in the ultrathin limit there is a non-zero FLT with a maximum torque conductivity -5.0E4 in the SI unit. When the Ir film thickness becomes comparable to or greater than its spin diffusion length, 1.6 nm, there is also a smaller bulk contribution to the fieldlike torque.

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Sutapa Dutta, Arnab Bose, A. A. Tulapurkar, R. A. Buhrman, D. C. Ralph. 2021-05-06. Interfacial and bulk spin Hall contributions to field-like spin-orbit torque generated by Iridium. https://doi.org/10.1103/physrevb.103.184416

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