  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 rule scaling: MR - (H/p0)m with m - 1.92 and the t-o temperature T under
different magnetic fields can also be scaled by T - (H-Hc)u with u = 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 dominant position.
