Extremely large magnetoresistance in the type-II Weyl semimetal MoTe2

We performed the angle dependent magnetoresistance (MR), Hall effect measurements, the temperature dependent magneto-thermoelectric power (TEP) S(T) measurements, and the first-principles calculations to study the electronic properties of orthorhombic phase MoTe2 (T-d - MoTe2), which was proposed to be electronically two dimensional (2D). There are some interesting findings about T-d - MoTe2. (1) A scaling approach epsilon(theta) = (sin(2)theta + gamma(-2) cos(2)theta)(1/2) is applied, where theta is the magnetic field angle with respect to the c axis of the crystal and gamma is the mass anisotropy. Unexpectedly, the electronically three-dimensional (3D) character with gamma as low as 1.9 is observed in T-d - MoTe2. (2) The possible Lifshitz transition and the following electronic structure change can be verified around T similar to 150K and T similar to 60 K, which is supported by the evidence of the slope changing of the temperature dependence of TEP, the carrier density extracted from Hall resistivity, and the onset temperature of gamma obtained from the MR measurements. The extremely large MR effect in T-d - MoTe2 could originate from the combination of the electron-hole compensation and a particular orbital texture on the electron pocket, which is supported by the calculations of electronic structure. Our results may provide a general scaling relation for the anisotropic MR and help to recognize the origins of the MR effect in other systems, such as the Weyl semimetals and the Dirac ones.