Spin‐orbit torques generated by exfoliated layers of the low‐symmetry semi‐metal ZrTe3are measured using the spin‐torque ferromagnetic resonance (ST‐FMR) technique. When the ZrTe3has a thickness greater than about 10 nm, artifacts due to spin pumping and/or resonant heating can cause the standard ST‐FMR analysis to overestimate the true magnitude of the torque efficiency by as much as a factor of 30, and to indicate incorrectly that the spin‐orbit torque depends strongly on the ZrTe3layer thickness. Artifact‐free measurements can still be achieved over a substantial thickness range by the method developed recently to detect ST‐FMR signals in the Hall geometry as well as the longitudinal geometry. ZrTe3/Permalloy samples generate a conventional in‐plane anti‐damping spin torque efficiency = 0.014 ± 0.004, and an unconventional in‐plane field‐like torque efficiency = 0.003 ± 0.001. The out‐of‐plane anti‐damping torque is negligible. It is suggested that artifacts similarly interfere with the standard ST‐FMR analysis for other van der Waals samples thicker than about 10 nm.
- Award ID(s):
- 1720633
- NSF-PAR ID:
- 10092657
- Date Published:
- Journal Name:
- Proceedings of SPIE
- Volume:
- 10732
- Page Range / eLocation ID:
- 37
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract -
null (Ed.)We measure spin-orbit torque generated by exfoliated layers of the low-symmetry semi-metal ZrTe3 using the spin-torque ferromagnetic resonance (ST-FMR) technique. When the ZrTe3 has a thickness greater than about 10 nm, artifacts due to spin pumping and/or resonant heating can cause the standard ST-FMR analysis to overestimate the true magnitude of the torque efficiency by as much as a factor of 30, and to indicate incorrectly that the spin-orbit torque depends strongly on the ZrTe3 layer thickness. Artifact-free measurements can still be achieved over a substantial thickness range by the method developed recently to detect ST-FMR signals in the Hall geometry as well as the longitudinal geometry. ZrTe3/Permalloy samples generate a conventional in-plane anti-damping spin torque efficiency ξDL|| = 0.014 ± 0.004, and an unconventional in-plane field-like torque efficiency |ξFL||| = 0.003 ± 0.001. The out-of-plane anti-damping torque is negligible. We suggest that artifacts similarly interfere with the standard ST-FMR analysis for other van der Waals samples thicker than about 10 nm.more » « less
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