Electronic structure of an antiferromagnetic metal: CaCrO3

We report on the electronic structure of the perovskite oxide CaCrO${}_{3}$ using valence-band, core-level, and Cr $2p\ensuremath{-}3d$ resonant photoemission spectroscopy (PES). Despite its antiferromagnetic order, a clear Fermi edge characteristic of a metal with dominant Cr $3d$ character is observed in the valence-band spectrum. The Cr $3d$ single-particle density of states are spread over 2 eV, with the photoemission spectral weight distributed in two peaks centered at $~$1.2 and 0.2 eV below $E$${}_{F}$, suggestive of the coherent and incoherent states resulting from strong electron-electron correlations. Resonant PES across the Cr $2p\ensuremath{-}3d$ threshold identifies a ``two-hole'' correlation satellite and yields an on-site Coulomb energy $U~$ 4.8 eV. The metallic DOS at $E$${}_{F}$ is also reflected through the presence of a well-screened feature at the low binding energy side of the Cr $2p$ core-level spectrum. X-ray-absorption spectroscopy at Cr $L$${}_{3,2}$ and O $K$ edges exhibit small temperature-dependent changes that point toward a small change in Cr-O hybridization. The Cr $2p$ core-level spectrum can be reproduced using cluster model calculations that include a charge transfer from the metallic screening channel at $E$${}_{F}$. The overall results indicate that CaCrO${}_{3}$ is a strongly hybridized antiferromagnetic metal, lying in the regime intermediate to Mott-Hubbard and charge-transfer systems.