Highly tunable Rashba spin-orbit coupling and crossover from weak localization to weak antilocalization in ionic-gated tellurium

Electrostatically gating various two-dimensional materials has shown different phase transitions upon changing their charge carrier density, which could provide an additional understanding about the fundamental properties of solids. Moreover, the gate voltage or electric field control of electron spin in materials with high spin-orbit coupling (SOC) is a key factor in the field of spintronics. In this paper, we performed electrostatic doping in $p$-type tellurium (Te) thin flakes using electric double-layer transistors (EDLTs). Our results show the possibility of gate tuning the insulator-metal phase transition in Te by effectively changing its charge carrier density. Furthermore, a crossover from weak localization (WL) to weak antilocalization (WAL) was observed, suggesting an increased Rashba-like SOC in the material created by a strong electric field restricted to the solid/electrolyte interface in EDLTs. The WAL becomes more pronounced as we increase the conductivity of the sample. The temperature dependence of the WAL further showed an $e\text{\ensuremath{-}}e$ interaction to be the main scattering mechanism of the quantum decoherence and dephasing in the material. More interestingly, we have demonstrated the ability to control the electron spin and increase the Rashba parameter by a factor of 4 through ionic gating $p$-type Te, which holds an intriguing potential for spintronics applications.