Magnetization dynamics in W/CoFeB, CoFeB/Pt and W/CoFeB/Pt multilayers was investigated using spin-orbit-torque ferromagnetic resonance (SOT-FMR) technique. An analytical model based on magnetization dynamics due to SOT was used to fit heavy metal (HM) thickness dependence of symmetric and antisymmetric components of the SOT-FMR signal. The analysis resulted in a determination of the properties of HM layers, such as spin Hall angle and spin diffusion length. The spin Hall angle of -0.36 and 0.09 has been found in the W/CoFeB and CoFeB/Pt bilayers, respectively, which add up in the case of W/CoFeB/Pt trilayer. More importantly, we have determined effective interfacial spin-orbit fields at both W/CoFeB and CoFeB/Pt interfaces, which are shown to cancel Oersted field for particular thicknesses of the heavy metal layers, leading to pure spin-current-induced dynamics and indicating the possibility for a more efficient magnetization switching.
@article{arxiv.1810.00641,
title = {Determination of spin Hall angle in heavy metal/CoFeB-based heterostructures with interfacial spin-orbit fields},
author = {Witold Skowroński and Łukasz Karwacki and Sławomir Ziętek and Jarosław Kanak and Stanisław Łazarski and Krzysztof Grochot and Tomasz Stobiecki and Piotr Kuświk and Feliks Stobiecki and Józef Barnaś},
journal= {arXiv preprint arXiv:1810.00641},
year = {2019}
}
Comments
8 pages, 4 figures, submitted to Physical Review Applied