Spin-Pumping-Free Determination of Spin-Orbit Torque Efficiency from Spin-Torque Ferromagnetic Resonance

Atsushi Okada, Yutaro Takeuchi, Kaito Furuya, Chaoliang Zhang, Hideo Sato, Shunsuke Fukami, Hideo Ohno

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Spin-torque ferromagnetic resonance (ST-FMR) provides a useful tool to investigate various magnetic properties in spintronic systems, where one excites FMR by applying a rf current and detects the dc voltage generated through rectification effects. While this scheme has been used to characterize spin-orbit torques (SOTs) that have attracted much attention recently, it is known that dc voltages can also be generated by spin pumping that overlaps with the signal from the rectification effects. Here, we show a method to determine the SOT generation efficiency by ST-FMR free from spin pumping using two representative material systems, W/Co-Fe-B/MgO and Pt/Co/MgO. In addition, using the values determined by the method, which are confirmed to agree well with the results of a separately performed extended harmonic Hall measurement, we also quantify the amount of overestimation if the results obtained by a conventional ST-FMR setup are analyzed without considering the spin pumping. The present finding offers a useful insight to obtain a reliable value of SOT efficiency using ST-FMR, in particular for systems that exhibit large SOT, which accompanies large spin pumping.

Original languageEnglish
Article number014040
JournalPhysical Review Applied
Issue number1
Publication statusPublished - 2019 Jul 23


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