Doping-induced nematic charge density wave in 1T-TiSe₂.

The ground state of pristine 1T-TiSe2 is known to be a commensurate 2x2x2 charge density wave, although its origin is still debated between the strong electron-phonon coupling and the excitonic insulator mechanism. While the generally accepted charge density wave respects the threefold symmetry of the lattice, some experiments display signatures of the breaking of this symmetry. We propose that these seemingly contradictory observations can be rationalized by a nematic charge density wave state induced by electron doping, which arises due to the competition between two order parameters. This scenario is supported by our microscopic mean-field calculations of an effective tight-binding model for monolayer 1T-TiSe2. Finally, we discuss the implications of our prediction in transport experiments.