Probing the metal-insulator transition of NdNiO₃ by electrostatic doping

Modulation of the charge carrier density in a Mott material by remote doping from a highly doped conventional band insulator is proposed to test theoretical predictions of band filling control of the Mott metal-insulator transition without introducing lattice distortions or disorder, as is the case for chemical doping. The approach is experimentally tested using ultrathin (2.5 nm) NdNiO₃ films that are epitaxially grown on La-doped SrTiO ₃ films. We show that remote doping systematically changes the charge carrier density in the NdNiO₃ film and causes a moderate shift in the metal-insulator transition temperature. These results are discussed in the context of theoretical models of this class of materials exhibiting a metal-insulator transition.