Quantum magnetic oscillations in Weyl semimetals with tilted nodes

TL;DR

This paper investigates how tilting Weyl nodes affects quantum magnetic oscillations in Weyl semimetals, revealing modifications in oscillation periods, magnetization behavior, and the influence of node energy shifts.

Contribution

It extends previous studies by analyzing the impact of tilt on magnetic oscillations and the quantum limit in Weyl semimetals, considering various tilt configurations and energy shifts.

Findings

Magnetization from a single Weyl node remains finite as B approaches zero.

The sign of magnetization depends on chirality and tilt orientation.

Different behaviors are observed for pairs of Weyl nodes with opposite or same tilt.

Abstract

A Weyl semimetal (WSM)\ is a three-dimensional topological phase of matter where pairs of nondegenerate bands cross at isolated points in the Brillouin zone called Weyl nodes. Near these points, the electronic dispersion is gapless and linear. A magnetic field $B$ changes this dispersion into a set of Landau levels which are dispersive along the direction of the magnetic field only. The $n=0$ Landau level is special since its dispersion$\ $is linear and unidirectional. The presence of this chiral level distinguishes Weyl from Schr\"{o}dinger fermions. In this paper, we study the quantum oscillations of the orbital magnetization and magnetic susceptibility in Weyl semimetals. We generalise earlier works% \cite{Mikitik2019} on these De Haas-Van Alphen oscillations by considering the effect of a tilt of the Weyl nodes. We study how the fundamental period of the oscillations in the small $B$ limit and the strength of the magnetic field $B_{1}$ required to reach the quantum limit are modified by the magnitude and orientation of the tilt vector $\mathbf{t}$. We show that the magnetization from a single node is finite in the $B\rightarrow 0$ limit. Its sign depends on the product of the chirality and sign of the tilt component along the magnetic field direction. We also study the magnetic oscillations from a pair of Weyl nodes with opposite chirality and with opposite or identical tilt. Our calculation shows that these two cases lead to a very different behavior of the magnetization in the small and large $B$ limits. We finally consider the effect of an energy shift $\pm \Delta _{0}$ of a pair of Weyl nodes on the magnetic oscillations. We assume a constant density of carriers so that both nodes share a common Fermi level. Our calculation can easily be extended to a WSM with an arbitrary number of pairs of Weyl nodes.