Nonlocal Measurement as a Probe of the Spin Hall Effect in Topological Insulators

Topological insulators (TIs) are promising candidates for alternative computing device designs. In particular, they have great potential for spintronic devices, where utilization of electron spin rather than charge would allow for lower-power and higher-performance computing in next-generation architectures. Efficient conversion between spin and charge signals is crucial to spintronic technology. TIs provide highly efficient spin-to-charge conversion, as a result of their unique topological properties. One way to electrically quantify conversion efficiency is with the spin Hall effect (SHE). Here, we present SHE measurements of the topological insulator Bi₂Te_2.5Se_0.5. Because of the topological nature of this material, we can measure the SHE without the use of ferromagnetic injectors or detectors. Using the nonlocal resistance, we measure spin Hall angles up to 2.4 with spin lifetimes up to 9 ps. Furthermore, ferromagnet-free measurement allows for quick diagnostics of the spin properties without the need to fabricate multilevel devices.