Gate-tunable strong spin-orbit interaction in two-dimensional tellurium probed by weak antilocalization

Tellurium (Te) has attracted great research interest due to its unique crystal structure since the 1970s. However, the conduction band of Te is rarely studied experimentally because of the p-type accumulation layer at the surface of Te. By the atomic layer deposited dielectric doping technique, we are able to access the conduction-band transport properties of Te in a controlled fashion. In this paper, we report on a systematic study of the weak-anti-localization (WAL) effect in n-type two-dimensional (2D) Te films. We find that WAL agrees well with Iordanskii, Lyanda-Geller, and Pikus theory. The gate and temperature-dependent WAL reveal that the D'yakonov-Perel mechanism, dominant for spin relaxation and phase relaxation, is governed by electron-electron interaction. A large phase-coherence length near 600 nm at T=1K is obtained together with gate-tunable spin-orbit interaction (SOI). Transition from weak-localization to WAL depending on gate bias is also observed. These results demonstrate that newly developed solution-based synthesized Te films provide a new controllable strong SOI 2D semiconductor with high potential for spintronic applications.