Fu-Kane-Mele monopoles in semimetals

TL;DR

This paper explores how Weyl points function as monopoles in semimetals with time-reversal symmetry, revealing their role in topological phase transitions and surface state topology, including the prediction of interface Dirac cones.

Contribution

It introduces Weyl points as monopoles and links their connectivity to the topology of semimetals and topological insulator transitions, providing a new classification approach.

Findings

Weyl points act as monopoles affecting semimetal topology

Connectivity of Weyl points classifies semimetals

Prediction of topological Dirac cones at Weyl semimetal interfaces

Abstract

In semimetals with time-reversal symmetry, the interplay between Weyl points and Fu-Kane-Mele indices results in coexisting surface Dirac cones and Fermi arcs that are transmutable without a topological phase transition. We show that Weyl points act as a new type of monopole, and that their connectivity is essential for capturing the full topology of semimetals and their role as intermediaries of topological insulator transitions. The history of Weyl point creation-annihilation provides a simple and mathematically equivalent way to classify semimetals, and directly prefigures the surface state topology. We further predict the possibility of a topological Dirac cone on the interface between two Weyl semimetals.