Spin-orbitronics at a topological insulator-semiconductor interface

T. Guillet; C. Zucchetti; A. Marchionni; A. Hallal; P. Biagioni; C. Vergnaud; A. Marty; M. Finazzi; F. Ciccacci; M. Chshiev; F. Bottegoni; M. Jamet

doi:10.1103/physrevb.101.184406

arXiv · 1911.10611

Spin-orbitronics at a topological insulator-semiconductor interface

T. Guillet·C. Zucchetti·A. Marchionni·A. Hallal·P. Biagioni·C. Vergnaud·A. Marty·M. Finazzi·F. Ciccacci·M. Chshiev·F. Bottegoni·M. Jamet

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Abstract

Topological insulators (TIs) hold great promises for new spin-related phenomena and applications thanks to the spin texture of their surface states. However, a versatile platform allowing for the exploitation of these assets is still lacking due to the difficult integration of these materials with the mainstream Si-based technology. Here, we exploit germanium as a substrate for the growth of Bi$_2$Se$_3$, a prototypical TI. We probe the spin properties of the Bi$_2$Se$_3$/Ge pristine interface by investigating the spin-to-charge conversion taking place in the interface states by means of a non-local detection method. The spin population is generated by optical orientation in Ge, and diffuses towards the Bi$_2$Se$_3$ which acts as a spin detector. We compare the spin-to-charge conversion in Bi$_2$Se$_3$/Ge with the one taking place in Pt in the same experimental conditions. Notably, the sign of the spin-to-charge conversion given by the TI detector is reversed compared to the Pt one, while the efficiency is comparable. By exploiting first-principles calculations, we ascribe the sign reversal to the hybridization of the topological surface states of Bi$_2$Se$_3$ with the Ge bands. These results pave the way for the implementation of highly efficient spin detection in TI-based architectures compatible with semiconductor-based platforms.

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T. Guillet, C. Zucchetti, A. Marchionni, A. Hallal, P. Biagioni, C. Vergnaud, A. Marty, M. Finazzi, F. Ciccacci, M. Chshiev, F. Bottegoni, M. Jamet. 2019-11-24. Spin-orbitronics at a topological insulator-semiconductor interface. https://doi.org/10.1103/physrevb.101.184406

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