Disorder and magnetoconductivity in tilted Weyl semimetals

Abstract

Gapless Weyl semimetals (WSMs) are a novel class of topological materials that host massless Weyl fermions as their low-energy excitations. When the Weyl cone is tilted, the Lorentz invariance is broken and the Lifshitz transition drives the system from type-I WSMs into type-II WSMs. Here, based on the lattice model, we perform a systematic numerical study of the effect of onsite disorder on the diagonal magnetoconductivity in tilted WSMs. We use the self-consistent Born approximation to calculate the disorder-induced self-energy and then apply the Kubo-Streda formula to calculate the diagonal magnetoconductivity. For the transverse magnetoconductivity σxx, the disorder is found to show distinct effects in the quantum limit regime and in the quantum oscillation regime of type-I WSMs, which could be understood from the Einstein's relationship. With strong disorder, σxx shows a linear relation with the inverse magnetic field 1 B , which exhibits certain robustness to both the Fermi energy and the Weyl cone tilting. For the longitudinal magnetoconductivity σzz, the strong disorder can break the positive magnetoconductivity as well as the Shubnikov-de Haas oscillations. By analyzing the spectral function, we find that the chiral anomaly is still preserved at strong disorder even when the Weyl cone is overtilted, as there is no gap opening around the Weyl nodes. The implications of our results for experiments are discussed. arXiv:2002.06292v1 [cond-mat.mes-hall]

Magneto-optic signatures in the gapped Dirac semimetal with mixed linear and parabolic dispersions of ZrTe5

“…But the two peaks have comparable heights, Re(σ We analyze the effect of the impurity scattering that is phenomenologically represented by τ −1 on Re(σ αα ). We can see that when τ −1 increases, the resonant peaks of Re(σ αα ) are blurred out and may be smoothened, which are consistent with the previous studies [27,30,36]. When τ −1 0.2 meV, the double-peak structures at the saddle points are clearly seen in Re(σ αα ).…”

“…1 2 = 11.5 meV, respectively, which agree with the experimental observations [24]. Compared with the previously proposed 2D conical model to describe ZrTe 5 [23,30,31], where the linear terms occur in the x-y plane and the parabolic term is along in the z direction, H(k) in equation (1) incorporates the linear as well as the parabolic terms in all three directions. When v z = ξ = 0, H(k) reduces to the 2D conical model.…”

“…The magneto-optical conductivity has been shown to be a valuable technique in identifying the band structures as well as the topological properties of various materials [27,[33][34][35][36][37]. We focus on the diagonal terms of the optical conductivity tensor, which can be calculated by using the linear-response Kubo formula [30,32],…”