Magnetic phases and unusual topological electronic structures of Weyl semimetals in strong interaction limit

TL;DR

This paper explores how strong electron-electron interactions in Weyl semimetals induce magnetic phases and lead to the emergence of double-Weyl nodes, revealing complex interplay between topology and magnetism.

Contribution

It demonstrates that strong interactions cause Weyl semimetals to become magnetic and generate double-Weyl nodes, a novel topological feature induced by correlations.

Findings

Weyl semimetals become magnetic under strong interactions.

Double-Weyl nodes can be realized in the correlated phase.

Quantum phase transition from SSDW to A-AFM involves disintegration of double-Weyl nodes.

Abstract

The interplay of electronic band structures and electron-electron interactions is known to brew new phases in condensed matter. In this paper, we investigate thermodynamic phases and corresponding electronic structures of the Weyl semimetal in the strong onsite Coulomb interaction limit. Based on a minimum model of the Weyl semimetal with two linear Weyl nodes, it is shown that generically the Weyl semimetal becomes magnetic in the presence of interactions. In particular, it is shown that the Dzyaloshinskii-Moriya exchange interaction is generally induced so that the A-type antiferromagnetic (A-AFM) phase and the spiral spin density wave (SSDW) states are two generic phases. Furthermore, we find that Weyl nodes proliferate and it is possible to doubly enhance the unusual properties of non-interacting Weyl semimetals through the realization of double-Weyl nodes in strong correlation limit. Specifically, it is shown that in the SSDW phase, linear Weyl nodes are tuned into double-Weyl nodes with the corresponding charges being $\pm 2$. As the spin-orbit coupling increases, a quantum phase transition occurs with the SSDW phase being turned into an A-AFM phase and at the same time, double-Weyl nodes are disintegrated into two pairs of linear Weyl nodes. Our results reveal the unusual interplay between the topology of electronic structures and magnetism in strongly correlated phases of Weyl semimetals.