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arXiv · 1607.03872

Surface state dominated spin-charge current conversion in topological insulator/ferromagnetic insulator heterostructures

Hailong Wang·James Kally·Joon Sue Lee·Tao Liu·Houchen Chang·Danielle Reifsnyder Hickey·Andre Mkhoyan·Mingzhong Wu·Anthony Richardella·Nitin Samarth
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Abstract

We report the observation of ferromagnetic resonance-driven spin pumping signals at room temperature in three-dimensional topological insulator thin films -- Bi2Se3 and (Bi,Sb)2Te3 -- deposited by molecular beam epitaxy on yttrium iron garnet thin films. By systematically varying the Bi2Se3 film thickness, we show that the spin-charge conversion efficiency, characterized by the inverse Rashba-Edelstein effect length (lambda_IREE), increases dramatically as the film thickness is increased from 2 quintuple layers, saturating above 6 quintuple layers. This suggests a dominant role of surface states in spin and charge interconversion in topological insulator/ferromagnet heterostructures. Our conclusion is further corroborated by studying a series of YIG/(BiSb)2Te3 heterostructures. Finally, we use the ferromagnetic resonance linewidth broadening and the inverse Rashba-Edelstein signals to determine the effective interfacial spin mixing conductance and lambda_IREE.

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Hailong Wang, James Kally, Joon Sue Lee, Tao Liu, Houchen Chang, Danielle Reifsnyder Hickey, Andre Mkhoyan, Mingzhong Wu, Anthony Richardella, Nitin Samarth. 2016-07-13. Surface state dominated spin-charge current conversion in topological insulator/ferromagnetic insulator heterostructures. https://doi.org/10.1103/physrevlett.117.076601

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