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arXiv · 1810.00641

Determination of spin Hall angle in heavy metal/CoFeB-based heterostructures with interfacial spin-orbit fields

Witold Skowroński·Łukasz Karwacki·Sławomir Ziętek·Jarosław Kanak·Stanisław Łazarski·Krzysztof Grochot·Tomasz Stobiecki·Piotr Kuświk·Feliks Stobiecki·Józef Barnaś
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Abstract

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.

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Witold Skowroński, Łukasz Karwacki, Sławomir Ziętek, Jarosław Kanak, Stanisław Łazarski, Krzysztof Grochot, Tomasz Stobiecki, Piotr Kuświk, Feliks Stobiecki, Józef Barnaś. 2018-10-01. Determination of spin Hall angle in heavy metal/CoFeB-based heterostructures with interfacial spin-orbit fields. https://doi.org/10.1103/physrevapplied.11.024039

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