Suppression of charge density wave in single layer TiSe2 by interfacial effect

The stability of charge density wave (CDW) in the two-dimensional limit offers crucial insights into strongly correlated electronic systems. Although reducing material dimensionality effectively modulates CDW states, the influence of substrate interface remains pivotal and warrants further investigation. In this study, we examine the evolution of CDW order in epitaxially grown single layer TiSe2 on different substrates. We observe that the 2 × 2 CDW order persists in single layer TiSe2 on bilayer graphene, yet it becomes suppressed when the material is interfaced with an SrTiO3(111) substrate. Notably, the CDW order is fully restored in bilayer TiSe2 films grown on SrTiO3(111) substrates. Through comparative analysis of the growth mode, thermal stability, and electron doping in TiSe2/SrTiO3(111) heterostructures, we attribute the suppression of the CDW phase to strong interfacial bonding between TiSe2 and the substrate. Our findings highlight the tunability of CDW via interfacial engineering in single layer transition metal dichalcogenides, paving the way for nanoscale control of correlated quantum states.