Electron doping effects on the metal-insulator transition in perovskite nickelates: the case of NdNiO3

The rich experimental phenomenology of rare earth perovskite nickelates has recently
attracted considerable attention, particularly because of interest in the physics of phase transitions in correlated oxides where electron-lattice coupling is essential. Nickelates exhibit a metal-insulator transition (MIT), peculiar magnetic behaviour, lattice distortions, charge ordering and the potential for additional carrier injection and lattice distortion by dopants. Substitutional doping has been used as a common method for electron doping. The resulting changes are still not fully understood and the exact mechanisms that drive the MIT are still under debate, as dopants also introduce lattice distortions. Our main aim is to investigate the effects of pure electron doping in single crystalline epitaxial NdNiO3, where Li doping is used as the electron source. Our research will shed light on the spectral origin of the occupied states and the physical source of MIT suppression. In particular, we will test the accuracy of the negative charge transfer description and identify the electronic states
observed for both the metallic and insulating phases.