Spin-orbit coupling and weak antilocalization in the thermoelectric material β-K₂Bi₈Se₁₃

We have studied the effect of spin-orbital coupling (SOC) on the electronic transport properties of the thermoelectric material β-K₂Bi ₈Se₁₃ via magnetoresistance measurements. We found that the strong SOC in this material results in the weak antilocalization (WAL) effect, which can be described well by a threedimensional weak localization model. The phase coherence length extracted from theoretical fitting exhibits a powerlaw temperature dependence, with an exponent around 2.1, indicating that the electron dephasing is governed by electron-transverse phonon interactions. As in topological insulators, the WAL effect in β-K₂Bi ₈Se₁₃ can be quenched by magnetic impurities (Mn) but is robust against nonmagnetic impurities (Te). Although our magnetotransport studies provide no evidence for topological surface states, our analyses suggest that SOC plays an important role in determining the thermoelectric properties of β-K₂Bi₈Se₁₃.