Observation of the Spin Seebeck Effect in Bi2Te3 Topological Insulator without an External Magnetic Field

The 3D topological insulator Bi2Te3 is a well‐known semiconductor material with a large Seebeck coefficient, and it is widely used in thermoelectric generators. The spin‐momentum‐locked surface states in topological insulator induce electronic spin polarization which may be used for spin generation and accumulation. Under a temperature gradient, the accumulation of surface electrons with opposite spin directions at the hot and cold sides of the sample will occur. Thus, the spin Seebeck effect (SSE) is detected through the inverse spin Hall effect in heavy metal Pt electrodes with a strong spin–orbit interaction. The SSE is observed in the topological insulator Bi2Te3 without application of an external magnetic field. The spin Seebeck coefficient in the Bi2Te3 topological insulator increases with increasing surface disorder, which is explained via the Dyakonov–Perel mechanism of the spin relaxation time. In this work, epitaxial layers of the topological insulator Bi2O3, grown on (001) GaAs, are studied for the presence of the spin Seebeck effect. The values of the Seebeck coefficient have opposite polarities on the hot and cold sides of the samples with Pt probe electrodes, whereas for Al electrodes the coefficient does not change sign. The spin Seebeck coefficient is largest for the most disordererd sample.