# Crystalline Weyl semimetal phase in Quantum Spin Hall systems under magnetic fields

## TL;DR

This paper predicts a new crystalline Weyl semimetal phase in quantum spin Hall systems under magnetic fields, characterized by a stable gapless phase protected by symmetries, and demonstrates its robustness even with symmetry-breaking.

## Contribution

It introduces the concept of a crystalline Weyl semimetal phase in QSH systems and analyzes its stability under symmetry-breaking conditions.

## Key findings

- Identification of a stable topological gapless phase in QSH systems under magnetic fields.
- Demonstration of the robustness of this phase even with particle-hole symmetry breaking.
- Prediction of observable topological phase transitions in Kane and Mele model materials.

## Abstract

We investigate an unconventional topological phase transition that occurs in quantum spin Hall (QSH) systems when applying an external in-plane magnetic field. We show that this transition between QSH and trivial insulator phases is separated by a stable topological gapless phase, which is protected by the combination of particle-hole and reflection symmetries, and thus, we dub it as crystalline Weyl semimetal. We explore the stability of this new phase when particle-hole symmetry breaking terms are present. Especially, we predict a robust unconventional topological phase transition to be visible for materials described by Kane and Mele model even if particle-hole symmetry is significantly broken.