Observation of inverse spin Hall effect in bismuth selenide

TLDR

Bismuth selenide is a topological insulator with helical spin polarization and strong spin‑orbit coupling that links charge currents to spin currents via the spin Hall effect. The authors built a Bi₂Se₃ spin detector by injecting a pure spin current from a magnetic permalloy layer into a Bi₂Se₃ thin film and measuring the resulting inverse spin Hall voltage. They measured a room‑temperature spin Hall angle of 0.0093 ± 0.0013 and a spin diffusion length of 6.2 ± 0.15 nm, indicating that such topological insulators can serve in functional spintronic devices.

Abstract

Bismuth Selenide $({\mathrm{Bi}}_{2}{\mathrm{Se}}_{3})$ is a topological insulator exhibiting helical spin polarization and strong spin-orbit coupling. The spin-orbit coupling links the charge current to spin current via the spin Hall effect (SHE). We demonstrate a ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ spin detector by injecting the pure spin current from a magnetic permalloy layer to a ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ thin film and detect the inverse SHE in ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$. The spin Hall angle of ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ is found to be 0.0093 \ifmmode\pm\else\textpm\fi{} 0.0013 and the spin diffusion length in ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ to be 6.2 \ifmmode\pm\else\textpm\fi{} 0.15 nm at room temperature. Our results suggest that topological insulators with strong spin-orbit coupling can be used in functional spintronic devices.