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-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-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 CaCrO₃ is a strongly hybridized antiferromagnetic metal, lying in the regime intermediate to Mott-Hubbard and charge-transfer systems.