Symmetries of Real and Imaginary Charge Density Wave States and Response Tensors in AV3Sb5 Kagome Metals

Abstract

Space group symmetries and multipole moments allowed by them can be used to not only classify different phases but also to predict the macroscopic response induced by structural or electronic order parameters. Similarly, magnetic space groups can be utilized to predict macroscopic response induced by magnetic orders. In this talk, we apply similar ideas to possible charge density wave orders in AV3Sb5 Kagome materials with time-reversal symmetry breaking imaginary charge density waves. After showing that charge density wave orders can be represented by magnetic irreducible representations of the space group, we tabulate the different phases induced by them, and predict experimental signatures therein. In particular, we focus on piezomagnetism and spontaneous gyrotropic birefringence and show that these two complimentary tensors can differentiate between most possible phases in Kagome compounds.