Ferroelectrically Controlled Chirality Switching of Weyl Quasiparticles

TL;DR

This paper proposes a ferroelectric mechanism to reversibly switch the chirality of Weyl phonons using electric fields, supported by symmetry analysis and first-principles calculations, enabling dynamic control of topological phononic properties.

Contribution

It introduces a novel ferroelectric approach to control Weyl phonon chirality, supported by symmetry analysis and material screening, advancing topological phononics research.

Findings

Identified 27 symmetry groups capable of hosting Weyl phonons with reversible chirality.

First-principles calculations found candidate ferroelectric materials, including K$_2$ZnBr$_4$, exhibiting chirality switching.

Reversal of ferroelectric polarization in these materials inverts Weyl point chirality and topological features.

Abstract

Weyl quasiparticles, as gapless low-energy excitations with nontrivial chirality, have garnered extensive interest in recent years. However, archieving effective and reversible control over their chirality (topological charge) remains a major challeng due to topological protection. In this work, we propose a ferroelectric mechanism to switch the chirality of Weyl phonons, where the reversal of ferroelectric polarization is intrinsically coupled to a simultaneous reversal of the chirality of Weyl points. This enables electric-field-driven control over the topological properties of phonon excitations. Through a comprehensive symmetry analysis of polar space groups, we identify 27 groups capable of hosting symmetry-protected Weyl phonons with chiral charges $C = 1$, $2$, and $3$, whose chirality can be reversed via polarization switching. The first-principles calculations are performed to screen feasible material candidates for each type of chirality, yielding a set of prototypical ferroelectric compounds that realize the proposed mechanism. As a representative example, K$_2$ZnBr$_4$ hosts the minimal configuration of two pairs of Weyl phonons. Upon polarization reversal, the chirality of all Weyl points is inverted, accompanied by a reversal of associated topological features such as Berry curvature and surface arcs. These findings provide a viable pathway for dynamic, electrical control of topological band crossings and open new avenues for chirality-based phononic applications.