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 ± 0.0013 and the spin diffusion length in ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ to be 6.2 ± 0.15 nm at room temperature. Our results suggest that topological insulators with strong spin-orbit coupling can be used in functional spintronic devices.

• Received 19 April 2014
• Revised 20 August 2014

DOI:https://doi.org/10.1103/PhysRevB.90.094403