Low-temperature phase transition in polar semimetal T_{d}−MoTe_{2} probed by nonreciprocal transport

We studied the nonreciprocal transport of layered MoTe_{2}, which undergoes a structural transition from centrosymmetric to the noncentrosymetric polar phase. Careful inspections of the temperature-dependent resistance showed an occurrence of additional phase transition at around T^{*}=50 K inside the noncentrosymmetric polar phase. We found that the nonreciprocal signal emerges below T^{*}, associated with the filling of the hole pocket. The present result suggests that the mechanism of the nonreciprocal transport is significantly distinct from that in simple polar semiconductors but is highly sensitive to the small hole pocket buried in the major carriers in semimetals.