Ideal type-II Weyl phonons in wurtzite CuI

TL;DR

This paper predicts the existence of ideal type-II Weyl phonons in wurtzite CuI, revealing topologically nontrivial phonon points that could lead to novel thermal transport phenomena and are experimentally observable.

Contribution

It demonstrates the first-principles prediction of ideal type-II Weyl phonons in noncentrosymmetric wurtzite CuI, distinct from electronic Weyl points and observable in experiments.

Findings

Six pairs of nontrivial Weyl points in phonon dispersion

Weyl phonons are isolated from bulk phonon continuum

Potential for observing Weyl phonon Hall effect

Abstract

Weyl semimetals exhibitinging the topologically nontrivial touching points in electronic band dispersion of solids pave the wave way to novel electronic devices and functionalities. Here, we demonstrate the signature of topologically nontrivial Weyl points (WPs) in phonon dispersion of solids through a first-principles investigations. ofT noncentrosymmetric wurtzite CuI (cuprous iodide at high temperature). These type-II phononic WP in phonon dispersion of wurtzite CuI is manifested in noncentrosymmetric wurtzite CuI by six pairs of the nontrivial touching points in the k_z=0.0 plane. The ideal WPs in phonon dispersion are completely isolated from bulk phonon continuum, are different distinct from many type-II WPs in electronic band dispersion of solids associated with the overlapping band states. The opposite chirality of Weyl phonon nodes with quantized Berry curvature are utilized forproduces Weyl phonon Hall effect, in analogous analogy towith valley Hall effect of electrons. Such ideal type-II Weyl phonons are phase is readily observable in experiment, and could provideing a unique platform to study novel thermal transport properties different distinct from that in type-I Weyl phonons phase.