Origin of the turn-on phenomenon in Td- MoTe2.

We did the resistivity and scanning tunneling microscope/spectroscopy (STM/STS) experiments at different temperatures and magnetic fields to investigate the origin of the turn-on (t-o) phenomenon of Td - MoTe2. There are two interesting observations. Firstly, magnetoresistance (MR) follows the Kohler's rule scaling: MR ~ (H/ρ0)m with m ≈ 1.92 and the t-o temperature T* under different magnetic fields can also be scaled by T* ~ (H - Hc)υ with υ = 1/2. Secondly, a combination of compensated electron-hole pockets and a possible electronic structure phase transition induced by the temperature have been validated in Td - MoTe2 by the STM/STS experiments. Compared with the STS of Td - MoTe2 single crystal under H = 0, the STS hardly changes even when the applied field is up to 7 T. The origins of the t-o phenomenon in Td - MoTe2 are discussed. Meanwhile, we analyzed the universality and applicability of the t-o phenomenon in the extreme MR materials with almost balanced hole and electron densities as well as with other systems where the density of hole or electron is in a dominant position. [ABSTRACT FROM AUTHOR]