Charge Doping and Quantum Monte Carlo of NiO

NiO is a Mott insulator that orders antiferromagnetically below 520 K¹. The transition temperature drops with Li-doping and becomes first ferrimagnetic and later antiferromagnetic with a Néel temperature of 9 K². Despite intense study of NiO and other Mott insulators, the evolution of correlations with charge doping, which give rise to spectacular phenomena (including superconductivity in cuprates), is poorly understood to date. Here, we combine atomic layer-by-layer molecular beam epitaxy growth of charge doped NiO with density functional theory (DFT) and Quantum Monte Carlo (QMC) simulations. We analyze the band gap with spectroscopic ellipsometry as a function of hole (K) and electron (In) doping, and compare the results with DFT and QMC. Moreover, we measure the distortion of the lattice caused by the large K with extended x-ray absorption fine structure and find a distortion much larger than predicted by DFT.

¹ D. Alders et al., EPL 32 (3), 259 (1995)
² P. T. Barton et al., Chem. Eur. J. 19 (43), 14521 (2013)