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arXiv · 1804.09930

Origin and evolution of surface spin current in topological insulators

André Dankert·Priyamvada Bhaskar·Dmitrii Khokhriakov·Isabel H. Rodrigues·Bogdan Karpiak·M. Venkata Kamalakar·Sophie Charpentier·Ion Garate·Saroj P. Dash
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Abstract

The Dirac surface states of topological insulators offer a unique possibility for creating spin polarized charge currents due to the spin-momentum locking. Here we demonstrate that the control over the bulk and surface contribution is crucial to maximize the charge-to-spin conversion efficiency. We observe an enhancement of the spin signal due to surface-dominated spin polarization while freezing out the bulk conductivity in semiconducting Bi1.5Sb0.5Te1.7Se1.3 below 100K. Detailed measurements up to room temperature exhibit a strong reduction of the magnetoresistance signal between 2 and 100K, which we attribute to the thermal excitation of bulk carriers and to the electron-phonon coupling in the surface states. The presence and dominance of this effect up to room temperature is promising for spintronic science and technology.

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André Dankert, Priyamvada Bhaskar, Dmitrii Khokhriakov, Isabel H. Rodrigues, Bogdan Karpiak, M. Venkata Kamalakar, Sophie Charpentier, Ion Garate, Saroj P. Dash. 2018-04-26. Origin and evolution of surface spin current in topological insulators. https://doi.org/10.1103/physrevb.97.125414

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