Superconductivity in monoclinic TiO film

Titanium oxide films garner substantial research attention among binary oxides since the superconducting transition temperature of cubic TiO significantly rises from around 2 K in bulk to 7.4 K in thin films. In this study, titanium oxide thin films were fabricated using magnetron sputtering on Al₂O₃ substrates, where spatially multiphase coexistence was observed. By incorporating a Gd-doped CeO₂ (GCO) buffer layer, we achieved the epitaxial growth of single-phase monoclinic TiO thin films, which exhibit a superconducting transition temperature of 5 K. Concurrently, a previously unreported superstructure is identified within the GCO intermediate layer, arising from oxygen vacancy ordering during heteroepitaxial growth. These findings confirm the emergence of superconductivity in the monoclinic titanium oxide system and provide valuable insights into elucidating the relationship between the structures and properties of various titanium oxides, as well as the ion redistribution mechanisms during the synthesis of complex oxide thin films.