Spin-orbit torque facilitates efficient magnetization switching via an in-plane current in perpendicularly magnetized heavy metal/ferromagnet heterostructures. The efficiency of spin-orbit-torque-induced switching is determined by the charge-to-spin conversion arising from either bulk or interfacial spin-orbit interactions, or both. Here, we demonstrate that the spin-orbit torque and the resultant switching efficiency in Pt/CoFeB systems are significantly enhanced by an interfacial modification involving Ti insertion between the Pt and CoFeB layers. Spin pumping and X-ray magnetic circular dichroism experiments reveal that this enhancement is due to an additional interface-generated spin current of the nonmagnetic interface and/or improved spin transparency achieved by suppressing the proximity-induced moment in the Pt layer. Our results demonstrate that interface engineering affords an effective approach to improve spin-orbit torque and thereby magnetization switching efficiency.
@article{arxiv.1803.06961,
title = {Enhanced spin-orbit torque via interface engineering in Pt/CoFeB/MgO heterostructures},
author = {Hae-Yeon Lee and Sanghoon Kim and June-Young Park and Young-Wan Oh and Seung-Young Park and Wooseung Ham and Yoshinori Kotani and Tetsuya Nakamura and Motohiro Suzuki and Teruo Ono and Kyung-Jin Lee and Byong-Guk Park},
journal= {arXiv preprint arXiv:1803.06961},
year = {2018}
}