Suppression of Charge Density Wave in Single Layer TiSe2 by Interfacial Effect

The stability of charge density wave (CDW) in the extreme two-dimensional limit provides critical insight into the comprehension of strongly correlated electronic systems. While reducing material dimensionality to the two-dimensional limit is effective for tuning CDW states, the role of the substrate interface remains critical and requires further exploration. Here, we study the modulation of CDW order in epitaxially grown single layer TiSe2 films on different substrates. While the 2 ´ 2 CDW order persists in single layer TiSe2 films on bilayer graphene, it is suppressed when interfaced with SrTiO3(111) substrate. Comparative analysis of growth mode, thermal stability and electron doping in TiSe2/SrTiO3(111) heterostructure suggests strong interfacial bonding between the TiSe2 film and the SrTiO3(111) substrate, which is responsible for the absence of the CDW phase. Our findings demonstrate the tunability of charge density wave by interfacial effect in single layer transition metal dichalcogenide, enabling the manipulation of the correlated quantum states at the nanoscale.