Sequential insulator-metal-insulator phase transitions of VO2 triggered by hydrogen doping
As a typical correlated oxide, V O 2 has attracted significant attentions due to its pronounced thermal-driven metal-insulator transition. Regulating electronic density through electron doping is an effective way to modulate the balance between competing phases in strongly correlated materials. However, the electron-doping triggered phase transitions in V O 2 as well as the intermediate states are not fully explored. Here, we report a controlled and reversible phase transition in V O 2 films by continuous hydrogen doping. Metallic and insulating phases are successively observed at room temperature as the doping concentration increases. The doped electrons linearly occupy V 3 d -O 2 p hybridized orbitals and consequently modulate the filling of the V O 2 conduction band edge states, resulting in the electron-doping driven continuous phase transitions. These results suggest the exceptional sensitivity of V O 2 electronic properties to electron concentration and orbital occupancy, providing key information for the phase transition mechanism.