Electronic structure of the kagome staircase compounds Ni3V2O8 and Co3V2O8

TL;DR

This study investigates the electronic structures of Ni3V2O8 and Co3V2O8 using advanced x-ray techniques, revealing differences in their d-band positions and electronic states, with implications for understanding their magnetic and electronic properties.

Contribution

The paper provides the first detailed experimental comparison of the electronic structures of Ni3V2O8 and Co3V2O8, combining x-ray spectroscopy with theoretical models to clarify their electronic states.

Findings

Ni and Co d bands are deeper than predicted, located in occupied O 2p and unoccupied V 3d regions.

Evidence of a dd excitation at 1.5 eV in Ni3V2O8, indicating weak V d occupancy.

Good agreement between experimental dd excitations and atomic multiplet theory predictions.

Abstract

The electronic structure of the kagome staircase compounds, Ni3V2O8 and Co3V2O8, has been investigated using soft x-ray absorption, soft x-ray emission, and resonant inelastic x-ray scattering (RIXS). Comparison between the two compounds, and with first principles band structure calculations and crystal-field multiplet models, provide unique insight into the electronic structure of the two materials. Whereas the location of the narrow (Ni,Co) d bands is predicted to be close to EF, we experimentally find they lie deeper in the occupied O 2p and unoccupied V 3d manifolds, and determine their energy via measured charge-transfer excitations. Additionally, we find evidence for a dd excitation at 1.5 eV in Ni3V2O8, suggesting the V d states may be weakly occupied in this compound, contrary to Co3V2O8. Good agreement is found between the crystal-field dd excitations observed in the experiment and predicted by atomic multiplet theory.