Nonlinear magnetotransport in MoTe2

The shape of the Fermi surface influences many physical phenomena in materials and a growing interest in how the spin-dependent properties are related to the fermiology of crystals has surged. Recently, a novel current-dependent nonlinear magnetoresistance effect, known as bilinear magnetoelectric resistance (BMR), has been shown to be not only sensitive to the spin texture in spin-polarized nonmagnetic materials, but also dependent on the convexity of the Fermi surface in topological semimetals. In this paper, we show that the temperature dependence of the BMR signal strongly depends on the crystal axis of the semimetallic MoTe2. For the a axis, the amplitude of the signal remains fairly constant, while for the b axis it reverses sign at about 100K. We calculate the BMR efficiencies at 10K to be χJA=173(3)nm2T-1A-1 and χJB=-364(13)nm2T-1A-1 for the a and b axis, respectively, and we find that they are comparable to the efficiencies measured for WTe2. We use density-functional theory calculations to compute the Fermi surfaces of both phases at different energy levels and we observe a change in convexity of the outermost electron pocket as a function of the Fermi energy. Our results suggest that the BMR signal is mostly dominated by the change in the Fermi-surface convexity.