Metal-insulator transition in epitaxial V1−xWxO2(≤x≤0.33) thin films

We have fabricated epitaxial V1−xWxO2(0≤x≤0.33) thin films on TiO2 (001) substrates. The metal-insulator transition temperature of VO2 is systematically reduced by W doping, and eventually a metallic ground state is realized at 0.08≤x≤0.09. Tiny resistivity upturn around 50 K observed for these films suggests an electronic phase separation between a majority metallic matrix and minority insulating puddles. With further increasing x above 0.095, another insulating phase appears while increasing the metal-insulator transition temperature. The elucidated phase diagram gives basic knowledge for devices based on Mott transition.