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Resonant Measurement of Nonreorientable Spin-Orbit Torque from a Ferromagnetic Source Layer Accounting for Dynamic Spin Pumping

Cornell Affiliated Author(s)

Author

Joseph Mittelstaedt
Daniel Ralph

Abstract

Using a multilayer containing a cobalt detector layer, a copper spacer, and a Permalloy source layer, we show experimentally how the nonreorientable spin-orbit torque generated by the Permalloy source layer - the component of spin-orbit torque that does not change when the Permalloy magnetization is rotated - can be measured using spin-torque ferromagnetic resonance (ST FMR) with line-shape analysis. We find that dynamic spin pumping between the magnetic layers exerts torques on the magnetic layers as large as, or larger than, the spin-orbit torques, so that if dynamic spin pumping is neglected, the result will be a large overestimate of the spin-orbit torque. Nevertheless, the two effects can be separated by performing ST FMR as a function of the frequency. We measure a nonreorientable spin torque ratio ζDL=0.04±0.01 for the spin-current flow from Permalloy through an 8-nm Cu spacer to the Co and a strength of dynamic spin pumping that is consistent with previous measurements by conventional ferromagnetic resonance. © 2021 American Physical Society.

Date Published

Journal

American Physical Society (APS)

Volume

16

Issue

2

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114621395&doi=10.1103%2fPhysRevApplied.16.024035&partnerID=40&md5=633f51e2422080ff26622ed08f670a90

DOI

10.1103/PhysRevApplied.16.024035

Group (Lab)

Dan C. Ralph Group

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