Abstract
Internodal dynamics of quasiparticles in Weyl semimetals manifest themselves in hydrodynamic, transport and thermodynamic phenomena and are essential for potential valleytronic applications of these systems. In an external magnetic field, coherent quasiparticle tunnelling between the nodes modifies the quasiparticle dispersion and, in particular, opens gaps in the dispersion of quasiparticles at the zeroth Landau level. We study magnetotransport in a Weyl semimetal taking into account mechanisms of quasiparticle scattering both affected by such gaps and independent of them. We compute the longitudal resistivity of a disordered Weyl semimetal with two nodes in a strong magnetic field microscopically and demonstrate that in a broad range of magnetic fields it has a strong angular dependence $\rho(\eta)\propto C_1+C_2 \cos^2\eta$, where $\eta$ is the angle between the field and the separation between the nodes in momentum space. The first term is determined by the coherent internodal tunnelling and is important only at angles $\eta$ close to $\pi/2$. This contribution depends exponentially on the magnetic field, $\propto \exp\left(-B_0/B\right)$. The second term is weakly dependent on the magnetic field for realistic concentrations of the impurities in a broad interval of fields.
Highlights
Recent prediction [1] and experimental discovery [2,3,4,5,6,7,8,9] of quasiparticles with Weyl dispersion in solid-state systems have motivated a vast number of predictions and observations of novel fundamental effects involving Weyl particles
We demonstrate that the gap 2, created in the quasiparticle dispersion by such tunnelling, significantly affects the longitudinal conduction of the quasiparticles if the magnetic field is perpendicular to the line connecting a pair of nodes in momentum space
The resistivity in the direction of the magnetic field exhibits a strong dependence, ∝ cos η2 + C, on the angle η between the direction of the magnetic field and the separation between the Weyl nodes in momentum space, where C 1 is a small constant determined by the hybridization of electron states between the nodes
Summary
Recent prediction [1] and experimental discovery [2,3,4,5,6,7,8,9] of quasiparticles with Weyl dispersion in solid-state systems have motivated a vast number of predictions and observations of novel fundamental effects involving Weyl particles (see, e.g., Refs. [10,11] for a review). Of fundamental importance for valleytronic applications is coherent tunnelling between Weyl nodes Such tunnelling leads to an effective coupling between the states of quasiparticles near different nodes, which may be controlled by the direction and the magnitude of an external magnetic field. This coupling leads to the opening of a gap in the quasiparticle dispersion at the zeroth Landau level in WSMs [37,38,39], which has recently been observed in experiment [40,41,42]. VI, we demonstrate that the conduction is strongly affected by the coupling if the magnetic field is perpendicular to the line connecting the nodes, and compute the resistivity in this regime
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