Ground state oxygen holes and the metal-insulator transition in the negative charge transfer rare-earth nickelates

Abstract

The metal-insulator transitions and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding of these materials remains elusive. Here, taking a NdNiO3 thin film as a representative example, we utilize a combination of x-ray absorption and resonant inelastic x-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of the rare-earth nickelates. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for the abundance of oxygen 2p holes in the ground state of these materials. Using cluster calculations and Anderson impurity model interpretation, we show that these distinct spectral signatures arise from a Ni 3d8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a conventional positive charge-transfer picture, but instead exhibit a negative charge-transfer energy, in line with recent models interpreting the metal to insulator transition in terms of bond disproportionation.

27 pages, 6 figures

References in corpus (6)

• Orbital order and possible superconductivity in LaNiO3/LaMO3 superlattices
• Role of magnetic and orbital ordering at the metal-insulator transition in NdNiO3
• Low-energy description of the metal-insulator transition in the rare-earth nickelates
• Electronic Transitions in Strained SmNiO_3 Thin Films
• Tailoring the electronic transitions of NdNiO_3 films through (111)_pc oriented interfaces
• Tuning the metal-insulator transition in NdNiO3 heterostructures via Fermi surface instability and spin-fluctuations

Cited by in corpus (12)

• Bond disproportionation and dynamical charge fluctuations in the perovskite rare earth nickelates
• Complex magnetic order in nickelate slabs
• Reproducibility and off-stoichiometry issues in nickelate thin films grown by pulsed laser deposition
• Crossover from Collective to Incoherent Spin Excitations in Superconducting Cuprates Probed by Detuned Resonant Inelastic X-ray Scattering
• Renormalization of effective interactions in a negative charge-transfer insulator
• Anomalous electron transport in epitaxial NdNiO${}_3$ films
• High pO2 Floating Zone Crystal Growth of the Perovskite Nickelate PrNiO3
• Resolving the nature of electronic excitations in resonant inelastic x-ray scattering
• Resonant inelastic x-ray scattering study of bond order and spin excitations in nickelate thin-film structures
• Anisotropic magnetic excitations and incipient Néel order in Ba(Fe${}_{1-x}$Mn${}_x$)${}_2$As${}_2$
• Unusual coexistence of negative/positive charge-transfer in mixed-valence Na${}_x$Ca${}_{1-x}$Cr${}_2$O${}_4$
• High resolution resonant inelastic EUV scattering from orbital excitations in a Heisenberg antiferromagnet