30 research outputs found
Core-Level X-Ray Spectroscopy of Infinite-Layer Nickelate: LDA+DMFT Study
Motivated by recent core-level x-ray photoemission spectroscopy (XPS), x-ray
absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS)
experiments for the newly-discovered superconducting infinite-layer nickelate,
we investigate the core-level spectra of the parent compounds NdNiO and
LaNiO using the combination of local density approximation and dynamical
mean-field theory (LDA+DMFT). Adjusting a charge-transfer energy to match the
experimental spectra, we determine the optimal model parameters and discuss the
nature of the NdNiO ground state. We find that self-doping from the Nd 5
states in the vicinity of the Fermi energy prohibits opening of Mott-Hubbard
gap in NdNiO. The present Ni XAS and RIXS calculation for LaNiO
cannot explain the difference to NdNiO spectra
Single- and Multimagnon Dynamics in Antiferromagnetic -FeO Thin Films
Understanding the spin dynamics in antiferromagnetic (AFM) thin films is
fundamental for designing novel devices based on AFM magnon transport. Here, we
study the magnon dynamics in thin films of AFM -FeO by
combining resonant inelastic x-ray scattering, Anderson impurity model plus
dynamical mean-field theory, and Heisenberg spin model. Below 100 meV, we
observe the thickness-independent (down to 15 nm) acoustic single-magnon mode.
At higher energies (100-500 meV), an unexpected sequence of equally spaced,
optical modes is resolved and ascribed to , 2, 3, 4, and 5
magnetic excitations corresponding to multiple, noninteracting magnons. Our
study unveils the energy, character, and momentum-dependence of single and
multimagnons in -FeO thin films, with impact on AFM magnon
transport and its related phenomena. From a broader perspective, we generalize
the use of L-edge resonant inelastic x-ray scattering as a multispin-excitation
probe up to . Our analysis identifies the spin-orbital mixing
in the valence shell as the key element for accessing excitations beyond
, and up to, e.g., . At the same time, we
elucidate the novel origin of the spin excitations beyond the ,
emphasizing the key role played by the crystal lattice as a reservoir of
angular momentum that complements the quanta carried by the absorbed and
emitted photons.Comment: Accepted in Physical Review
Analyzing the Local Electronic Structure of CoO Using 2p3d Resonant Inelastic X-ray Scattering
We present the cobalt 2p3d resonant inelastic X-ray scattering (RIXS) spectra of CoO. Guided by multiplet simulation, the excited states at 0.5 and 1.3 eV can be identified as the T excited state of the tetrahedral Co and the T excited state of the octahedral Co, respectively. The ground states of Co and Co sites are determined to be high-spin A(T) and low-spin A(O), respectively. It indicates that the high-spin Co is the magnetically active site in CoO. Additionally, the ligand-to-metal charge transfer analysis shows strong orbital hybridization between the cobalt and oxygen ions at the Co site, while the hybridization is weak at the Co site