Hopf-link multi-Weyl-loop topological semimetals

TL;DR

This paper develops a unified model for multi-Weyl-loop topological semimetals, analyzing their surface states and Landau levels to distinguish different topological configurations like Hopf-link states.

Contribution

It introduces a comprehensive two-band model that encompasses various multi-Weyl-loop semimetals, including Hopf-link, nodal-net, and nodal-chain states, and explores their surface and Landau level properties.

Findings

Hopf-link states exhibit a quadruply degenerate zero-energy Landau band.

The model unifies analysis of different multi-Weyl-loop semimetals.

Surface states vary among different topological configurations.

Abstract

We construct a generic two-band model which can describe topological Weyl semimetals with multiple closed Weyl loops. All the existing multi-Weyl-loop semimetals including the nodal-net, or nodal-chain and Hopf-link states can be examined within one same framework. Based on a two-loop model, the corresponding drum-head surface states for these topologically different bulk states are studied and compared with each other. The connection of our model with Hopf insulators is also discussed. Furthermore, to identify experimentally these topologically different Weyl semimetal states, especially distinguish the Hopf-link from unlinked ones, we also investigate their Landau levels. It is found that the Hopf-link state can be characterized by the existence of a quadruply degenerate zero-energy Landau band, regardless of the direction of the magnetic field.