Spin-orbit interaction effect in the electronic structure of \BiTe \ observed by angle-resolved photoemission spectroscopy

TL;DR

This study uses angle-resolved photoemission spectroscopy to reveal how spin-orbit interaction influences the electronic structure of p-type doped BiTe, shedding light on its thermoelectric properties.

Contribution

It provides direct experimental evidence of the role of spin-orbit interaction in BiTe's electronic structure and identifies surface states induced by band bending.

Findings

Band edges are off the $ ext{Γ}$-Z line, indicating spin-orbit interaction's importance.

Surface states form within an hour after cleaving, due to band bending.

Surface band bending may be caused by inter-layer distance changes.

Abstract

The electronic structure of $p$-type doped \BiTe is studied by angle resolved photoemission spectroscopy (ARPES) to experimentally confirm the mechanism responsible for the high thermoelectric figure of merit. Our ARPES study shows that the band edges are located off the $\Gamma$-Z line in the Brillouin zone, which provides direct observation that the spin-orbit interaction is a key factor to understand the electronic structure and the corresponding thermoelectric properties of \BiTe. Successive time dependent ARPES measurement also reveals that the electron-like bands crossing E$_F$ near the $\underline{\Gamma}$ point are formed in an hour after cleaving the crystals. We interpret these as surface states induced by surface band bending, possibly due to quintuple inter-layer distance change of \BiTe.