Observation of charge-to-spin conversion with giant efficiency at Ni$_{0.8}$Fe$_{0.2}$/Bi$_{2}$WO$_{6}$ interface

Saikat Das; Satoshi Sugimoto; Varun Kumar Kushwaha; Yusuke Kozuka; Shinya Kasai

doi:10.1063/5.0142695

paper

Observation of charge-to-spin conversion with giant efficiency at Ni $_{0.8}$ Fe $_{0.2}$ /Bi $_{2}$ WO $_{6}$ interface

arXiv:2304.02751 · doi:10.1063/5.0142695

Abstract

Magnetization switching using spin-orbit torque offers a promising route to developing non-volatile memory technologies. The prerequisite, however, is the charge-to-spin current conversion, which has been achieved traditionally by harnessing the spin-orbit interaction in heavy metals, topological insulators, and heterointerfaces hosting a high-mobility two-dimensional electron gas. Here, we report the observation of charge-to-spin current conversion at the interface between ferromagnetic Ni $_{0.8}$ Fe $_{0.2}$ and ferroelectric Bi $_{2}$ WO $_{6}$ thin films. The resulting spin-orbit torque consists of damping-like and field-like components, and the estimated efficiency amounts to about 0.48 $\pm$ 0.02, which translates to 0.96 $\pm$ 0.04 nm $^{- 1}$ in terms of interfacial efficiency. These numbers are comparable to contemporary spintronic materials exhibiting giant spin-orbit torque efficiency. We suggest that the Rashba Edelstein effect underpins the charge-to-spin current conversion on the interface side of Ni $_{0.8}$ Fe $_{0.2}$ . Further, we provide an intuitive explanation for the giant efficiency in terms of the spin-orbit proximity effect, which is enabled by orbital hybridization between W and Ni (Fe) atoms across the interface. Our work highlights that Aurivillius compounds are a potential addition to the emerging transition metal oxide-based spin-orbit materials.

arXiv comment20 pages

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Observation of charge-to-spin conversion with giant efficiency at Ni0.8​Fe0.2​/Bi2​WO6​ interface

Abstract

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Observation of charge-to-spin conversion with giant efficiency at Ni $_{0.8}$ Fe $_{0.2}$ /Bi $_{2}$ WO $_{6}$ interface