paper

Pb (=Pd,Pt and =S,Se) with transition metal kagome net: Dynamical properties, phonon nodal line, phonon surface states, and chiral phonons

arXiv:2303.13328 · doi:10.1002/apxr.202300025

Abstract

Shandite with NiPbS chemical formula and Rm symmetry, contains the kagome sublattice formed by the transition metal atoms. Recent experimental results confirmed the possibility of successfully synthesizing PdPb (=S,Se) with the same structure. In this paper, we theoretically investigate the dynamical properties of such compounds. Furthermore, we study the possibility of realizing PtPb with the shandite structure. We show that the PdPb{\it Ch} and PtPbS are stable with Rm symmetry. In the case of PtPbS, there is a soft mode, which is the source of the structural phase transition from Rm to Rc symmetry, related to the distortion within the kagome sublattice. We discuss realized phonon nodal lines in the bulk phonon dispersions in upper frequency modes. We show that the shandite structure can host the phonon surface states, with strong dependence by the surface kind. Additionally, chiral phonons with circular motion of the Pb atoms around the equilibrium position are realized.

14 pages, 10 figures

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