Signatures of the charge density wave collective mode in the infrared optical response of VSe 2

The layered transition-metal dichalcogenide VSe${}_{2}$ undergoes a phase transition from a good metal to a charge density wave phase. Recent advances in crystal growth enable a detailed study of the imprint of the charge density wave on the optical conductivity. The authors observe emerging infrared active phonon modes and a mass enhancement of the charge carriers due to the interaction with the lattice. They identify key signatures of the elusive sliding mode associated with the charge order in this material.