28 August 2014 Dual-frequency ferromagnetic resonance to measure spin current coupling in multilayers
Author Affiliations +
Spin pumping is a method for injecting a pure spin current into a non-magnetic metal (NM) by inducing precession of a neighboring ferromagnet (FM) at its ferromagnetic resonance frequency. A popular method to detect spin current uses the Inverse Spin Hall Effect (ISHE) to convert the spin current to a detectable charge current and hence a voltage. In order to better understand the role of time independent and high frequency contributions to spin pumping, we sought to detect we attempt to detect spin currents by using a second microwave frequency to detect changes in linewidth of a second ferromagnet due to the spin-torque induced by the spin current from the first ferromagnet. This dual resonance is achieved by pairing a custom broadband coplanar transmission line with the high-Q resonant cavity of a commercial electron paramagnetic resonance spectrometer. This technique is general enough that it should enable the investigation of spin currents in any FM-NM-FM system, for any orientation of external field, and is not sensitive to voltage artifacts often found in ISHE measurements. We find that the condition for simultaneous resonance generates a dc spin current that is too small to produce a measurable change in linewidth of the second ferromagnet, confirming the dominance of ac spin currents in linewidth enhancement measurements.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rohan Adur, Rohan Adur, Chunhui Du, Chunhui Du, Hailong Wang, Hailong Wang, Sergei A. Manuilov, Sergei A. Manuilov, Fengyuan Yang, Fengyuan Yang, P. Chris Hammel, P. Chris Hammel, "Dual-frequency ferromagnetic resonance to measure spin current coupling in multilayers", Proc. SPIE 9167, Spintronics VII, 91672J (28 August 2014); doi: 10.1117/12.2066174; https://doi.org/10.1117/12.2066174

Back to Top