Quantum Oscillations and Magnetoresistance in Type-II Weyl Semimetals - Effect of a Field Induced Charge Density Wave

Abstract

Recent experiments on type-II Weyl semimetals such as WTe${}_2$, MoTe${}_2$, Mo${}_x$W${}_{1-x}$Te${}_2$ and WP${}_2$ reveal remarkable transport properties in presence of a strong magnetic field, including an extremely large magnetoresistance and an unusual temperature dependence. Here, we investigate magnetotransport via the Kubo formula in a minimal model of a type-II Weyl semimetal taking into account the effect of a charge density wave (CDW) transition, which can arise even at weak coupling in the presence of a strong magnetic field because of the special Landau level dispersion of type-II Weyl systems. Consistent with experimental measurements we find an extremely large magnetoresistance with close to $B^2$ scaling at particle-hole compensation, while in the extreme quantum limit there is a transition to a qualitatively new scaling with approximately $B^{0.75}$. We also investigate the Shubnikov-de Haas effect and find that the amplitude of the resistivity quantum oscillations are greatly enhanced below the CDW transition temperature which is accompanied by an unusual non-monotonous (non-Lifshitz-Kosevich) temperature dependence.

9 pages, 5 figures