Interfacial eg orbital reconstruction: Modulation of Metal-Insulator transitions of ultrathin NdNiO3 films by two-dimensional electronic gas

Tunable metal-insulator transitions (MIT) of ultrathin NdNiO3 (NNO) film grown on the LaAlO3/SrTiO3 twodimensional electronic gas structures have been investigated by interfacial eg orbital reconstruction. Spectroscopy studies suggest that the polar catastrophe of the two-dimensional electronic gas results in Ni2+ to Ni3+ charge transfer of the NNO owing to the band-alignment condition. The orbital-hybridization of Ni 3d and O 2p can directly increase in-plane eg orbital occupancy, and the physical mechanism and modulation of the MIT can be clearly elucidated. This study not only provides new insight into the relationship between the electronic properties and orbital occupation, but it will also promote future application of epitaxial NNO thin films.

Automated summary

The tunable metal-insulator transitions (MIT) of ultrathin NdNiO3 (NNO) film grown on the LaAlO3/SrTiO3 two-dimensional electronic gas structures have been investigated through interfacial eg orbital reconstruction. Spectroscopy studies indicate that the polar catastrophe of the two-dimensional electronic gas leads to Ni2+ to Ni3+ charge transfer in NNO, facilitated by band-alignment conditions. The hybridization of Ni 3d and O 2p orbitals directly increases in-plane eg orbital occupancy, providing insight into the physical mechanism and modulation of the MIT.