Electronic structure of monolayer TiTe₂ thin films studied by high-resolution ARPES

Atomically-thin transition-metal dichalcogenides (TMDs) have attracted much attention since they show exotic quantum phenomena associated with two-dimensionalities, such as unconventional charge-density waves (CDW) and Ising superconductivity. Among TMDs, 1T-TiTe₂ with the octahedral structure has been a target of intensive studies since monolayer 1T-TiTe₂ undergoes CDW transition with (2×2) periodicity, while CDW vanishes in bilayer or thicker films. To elucidate the origin and the layer dependence of CDW transition, we have fabricated monolayer TiTe₂ on bilayer graphene by molecular-beam-epitaxy method and studied their electronic states by micro-focused angle-resolved photoemission spectroscopy. We clearly observed the semi-metallic nature and CDW-induced band folding in monolayer 1T-TiTe₂. In this talk, we will discuss the possibility of controlling the CDW phase transition by precisely tuning the carrier concentration.