The $A$-site-ordered cubic perovskite $\mathrm{LaC}{\mathrm{u}}_3\mathrm{C}{\mathrm{r}}_4{\mathrm{O}}_{12}$, where a partial Cu-Cr intersite charge transfer transition occurs at $T_{\mathrm{CT}}=220\mathrm{K}$, was found to be an unconventional metallic and $G$-type antiferromagnetic oxide. Neutron powder diffraction revealed a $G$-type antiferromagnetic ordering at the Cr sites and no ordered moments at the Cu sites. Ab initio electronic structure calculations revealed that the narrowing of the Cr-O-Cr bands due to heavy tilting of the $\mathrm{Cr}{\mathrm{O}}_6$ octahedra and the strong hybridization of the $\mathrm{Cu}\text{−}3d,\mathrm{Cr}\text{−}3d$, and $\mathrm{O}\text{−}2p$ orbitals near the Fermi level give an unusual electronic structure in the vicinity of a localized-electron regime. The $G$-type magnetic structure is primarily stabilized by nearest-neighbor antiferromagnetic superexchange interactions of the near-localized Cr spins. The ferromagnetic $\left\{111\right\}$ layers of the $G$-type antiferromagnetic Cr-spin sublattice allow the spin-polarized electron transfer through the strongly hybridized Cu orbitals.

• Received 26 July 2015
• Revised 15 September 2016

DOI:https://doi.org/10.1103/PhysRevB.95.041109