Momentum-resolved EELS study of lattice excitations in 1T-TaS₂

1T-TaS₂ is a well-known quasi two-dimensional (2D) transition metal dichalcogenide that exhibits three charge density wave (CDW) phases. At T<180K, this material enters a commensurate phase usually interpreted as a Mott insulator, which is often cited as a candidate quantum spin liquid. However, little is known about the charge excitations of 1T-TaS₂ at nonzero momentum, q. Here, we present a study of the meV-scale charge excitations of this material using momentum-resolved EELS (M-EELS). The spectrum consists of one acoustic and two optical phonon branches whose dispersion is influenced by the CDW wave vector. I will discuss how these excitations evolve with temperature and their relevance to the formation of the Mott state.