The spin orbital torques in Ta/CoFeB/MgO structures are experimentally investigated utilizing the planar Hall effect and magnetoresistance measurement. By angular field characterization of the planar Hall resistance at ±current, the differential resistance which is directly related to the spin orbital torques is derived. Upon curve fitting of the analytical formulas over the experimental results, it is found that the anti-damping torque, also known as spin Hall effect, is sizable while a negligible field-like torque is observed. A spin Hall angle of about 18 ± 0.6% is obtained for the Ta layer. Temperature dependent study of the spin orbital torques is also performed. It is found that temperature does not significantly modify the spin Hall angle. By cooling down the sample down to 100 K, the obtained spin Hall angle has a maximum value of about 20.5 ± 0.43%.
Bibliographical noteFunding Information:
This work was partially supported by the National Science Foundation Nanoelectronics Beyond 2020 (Grant No. NSF NEB 1124831), NSF MRSEC Program at University of Minnesota (Grants No. DMR-0819885), and by the C-SPIN center, one of six STARnet program research centers. A portion of this work was carried out in the Minnesota Nano Center.
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