Dynamical study of the origin of the charge density wave in AV 3 Sb 5 (A= K, Rb, Cs) compounds

摘要: Systems containing the ideal kagome lattice can exhibit several distinct and novel exotic states of matter. One example of such systems is a recently discovered (, Rb, and Cs) family of compounds. Here the coexistence of the charge density wave (CDW) and superconductivity is observed. In this paper, we study the dynamic properties of the systems in context of origin of the CDW phase. We show and discuss the structural phase transition from to symmetry that is induced by the presence of phonon soft modes. We conclude that the CDW observed in this family of compounds is a consequence of the atom displacement, from the high-symmetry position of the kagome net, in the low-temperature phase. Additionally, using the numerical ab initio methods, we discuss the charge distribution on the surface. We show that the observed experimental stripelike modulation of the surface …