Tunable double-Weyl Fermion semimetal state in the SrSi$_2$ materials class

TL;DR

This paper investigates the topological electronic structures of SrSi$_2$ materials, revealing a tunable double-Weyl Fermion state through doping, with potential for exploring Weyl semimetal properties.

Contribution

It demonstrates the tunability of double-Weyl Fermion states in SrSi$_2$ alloys via first-principles calculations, highlighting their potential as platforms for topological semimetal research.

Findings

Ca doping induces a double-Weyl semimetal with large Fermi arcs

Ba doping causes a transition to a gapped insulator

The topological phase diagram depends on lattice constant variations

Abstract

We discuss first-principles topological electronic structure of noncentrosymmetric SrSi$_2$ materials class based on the hybrid exchange-correlation functional. Topological phase diagram of SrSi$_2$ is mapped out as a function of the lattice constant with focus on the semimetal order. A tunable double-Weyl Fermion state in Sr$_{1-x}$Ca$_{x}$Si$_2$ and Sr$_{1-x}$Ba$_{x}$Si$_2$ alloys is identified. Ca doping in SrSi$_2$ is shown to yield a double-Weyl semimetal with a large Fermi arc length, while Ba doping leads to a transition from the topological semimetal to a gapped insulator state. Our study indicates that SrSi$_2$ materials family could provide an interesting platform for accessing the unique topological properties of Weyl semimetals.