Strong spin-orbit-interaction probed by weak antilocalization in p-type 2D Te under pressure

Elemental tellurium, with chiral non-centrosymmetric crystal structure and radial spin polarized Fermi surface, is of great interest in condensed matter physics. Previous studies show that it undergoes a pressure-induced Lifshitz transition at around 0.5GPa, where the camelback-like valence band transforms into the normal parabolic band, and a subsequent topological phase transition from a semiconductor to a Weyl semimetal enabled by the bandtouching at around 2GPa. Here we report a systematic study of the weak-anti-localization (WAL) effect in p-type 2D Te films under high pressure up to 2GPa. The pressure dependent WAL reveals the strengthen of the spin-orbit interaction (SOI) as pressure increases, with gate tunability. And the temperature dependent WAL confirms that the D’yakonov-Perel mechanism, dominant for spin relaxation and phase relaxation, is governed by electron-electron interaction. These results demonstrate strong tunable SOI in the valence band of 2D Te and provide insights into the SOI evolution during the Lifshitz transition and topological phase transition.