Weyl Node and Spin Texture in Trigonal Tellurium and Selenium

TL;DR

This paper investigates Weyl nodes and unique spin textures in trigonal tellurium and selenium, revealing their Weyl semimetal phase under pressure and the evolution of spin textures linked to Weyl node dynamics.

Contribution

It demonstrates the existence of Weyl nodes and hedgehog spin textures in Te and Se, and shows how pressure induces a Weyl semimetal phase in these materials.

Findings

Weyl nodes are present near the Fermi level in Te and Se.

The spin texture around H points is radial, forming a hedgehog pattern.

Pressure induces a Weyl semimetal phase and alters spin textures.

Abstract

We study Weyl nodes in materials with broken inversion symmetry. We find based on first-principles calculations that trigonal Te and Se have multiple Weyl nodes near the Fermi level. The conduction bands have a spin splitting similar to the Rashba splitting around the H points, but unlike the Rashba splitting the spin directions are radial, forming a hedgehog spin texture around the H points, with a nonzero Pontryagin index for each spin-split conduction band. The Weyl semimetal phase, which has never been observed in real materials without inversion symmetry, is realized under pressure. The evolution of the spin texture by varying the pressure can be explained by the evolution of the Weyl nodes in k space.