Investigation of the spin state of Co inLaCoO3at room temperature:Ab initiocalculations and high-resolution photoemission spectroscopy of single crystals

Abstract

We investigate the spin state of $\mathrm{La}\mathrm{Co}{\mathrm{O}}_{3}$ using state-of-the-art photoemission spectroscopy and ab initio band structure calculations. The $\mathrm{GGA}+U$ calculations provide a good description of the ground state for the experimentally estimated value of electron correlation strength $U$. In addition to the correlation effect, spin-orbit interaction is observed to play a significant role in the case of intermediate spin and high spin configurations. The comparison of the calculated $\mathrm{Co}\phantom{\rule{0.2em}{0ex}}3d$ and $\mathrm{O}\phantom{\rule{0.2em}{0ex}}2p$ partial density of states with the experimental valence band spectra indicates that at room temperature, Co has dominant intermediate spin state configuration and that the contribution from high spin configuration may not be significant at this temperature. The line shape of the $\mathrm{La}\phantom{\rule{0.2em}{0ex}}5p$ and $\mathrm{O}\phantom{\rule{0.2em}{0ex}}2s$ core level spectra could be reproduced well within these ab initio calculations.