Nonlinear magnetotransport in MoTe${}_2$

TL;DR

This study investigates the temperature-dependent nonlinear magnetoresistance in MoTe₂, revealing that Fermi surface convexity significantly influences the bilinear magnetoelectric resistance, with implications for understanding spin-dependent transport.

Contribution

The paper demonstrates how Fermi surface convexity affects BMR in MoTe₂ and provides detailed experimental and theoretical analysis of its temperature and crystal axis dependence.

Findings

BMR amplitude remains constant along the a-axis with temperature.

BMR reverses sign along the b-axis around 100 K.

Fermi surface convexity change correlates with BMR variations.

Abstract

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 non-magnetic 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 MoTe${}_2$. For the a-axis, the amplitude of the signal remains fairly constant, while for the b-axis it reverses sign at about 100 K. We calculate the BMR efficiencies at 10 K to be $\chi^{J}_{A} = (100\pm3)$ nm${}^2$T${}^{-1}$A${}^{-1}$ and $\chi^{J}_{B} = (-364\pm13)$ nm${}^2$T${}^{-1}$A${}^{-1}$ for the a- and b-axis, respectively, and we find that they are comparable to the efficiencies measured for WTe${}_2$. 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 outer-most 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.