The Hall coefficients of 1T-TaS2 and 1T-TaSe2 single crystals were measured from 360 K to 1.4 K. An abrupt change of the sign and a hysteresis were observed in the Hall coefficient of 1T-TaS2 at the nearly commensurate-commensurate phase transition temperature, ca. 200 K; above this ...
Surprisingly, however, at large spin-orbit coupling, the system undergoes a topological phase transition and enter into a new topological phase protected by a pseudo- spin Chern number, which can be viewed as a persistent extension of the quantum spin Hall phase upon doping. From bulk-edge ...