# High-pressure synthesis of an unusual antiferromagnetic metal CaCoO$_{3}$ with GdFeO$_{3}$-type perovskite structure

## TL;DR

This study reports the high-pressure synthesis of CaCoO$_{3}$, a GdFeO$_{3}$-type perovskite with antiferromagnetic order at 95 K, highlighting the magnetic phase diversity of Co$^{4+}$-perovskites influenced by lattice distortion.

## Contribution

It introduces a novel high-pressure synthesis method for CaCoO$_{3}$ with a detailed structural and magnetic characterization, revealing new magnetic phases in Co$^{4+}$-perovskites.

## Key findings

- CaCoO$_{3}$ is an antiferromagnetic metal with T_N = 95 K.
- The compound has a GdFeO$_{3}$-type perovskite structure with Co in +4 oxidation state.
- The material maintains an incoherent metallic state down to low temperatures.

## Abstract

The GdFeO$_{3}$-type perovskite CaCoO$_{3}$ has been successfully synthesized by high-pressure oxygen annealing for the oxygen deficient perovskite. A detailed structural analysis based on synchrotron X-ray diffraction data and a thermogravimetric analysis show that the valence of Co is +4 and the sample is free from oxygen deficiency. This compound shows an antiferromagnetic ordering at 95 K, which has presumably helical spin arrangement, with keeping the incoherent metallic state down to the lowest temperature. This work demonstrates that the Co$^{4+}$-perovskite oxides exhibit a variety of magnetic phases by the band-width control through the lattice distortion.