Weyl Phonons in Condensed Matter: A First-Principles Perspective

Weyl phonons, which simultaneously possess topological and chiral degrees of freedom, have attracted increasing attention in recent years. Based on their topological charge, dispersion characteristics, and symmetry protection mechanisms, Weyl points can be classified into conventional and unconventional types. In this review, we first introduce the research background of Weyl phonons, tracing their development from studies on Weyl semimetals. We then present a selection of representative first-principles studies on Weyl phonons, following a progression from conventional single Weyl phonons to unconventional multi-Weyl phonons, including quadratic Weyl phonons, triple Weyl phonons, and charge-four Weyl phonons. Finally, we provide an outlook on future research directions, including their potential impact on thermal transport and phononic device applications. We hope this review serves as a comprehensive guide for current research on Weyl phonons and provides insights into the rich topological structures emerging in phononic systems. .