Interplay between Jahn-Teller instability, uniaxial magnetism and ferroelectricity in Ca3CoMnO6

TL;DR

This study uses density functional theory to explore how Jahn-Teller distortions influence the magnetic and ferroelectric properties of Ca3CoMnO6, revealing complex interactions between structural distortions and magnetic anisotropy.

Contribution

It demonstrates the role of Jahn-Teller distortion in affecting uniaxial magnetism and ferroelectricity in Ca3CoMnO6, providing insights into the interplay of these phenomena.

Findings

Jahn-Teller distortion removes C3 symmetry and affects magnetism.

High-spin Co2+ ions retain orbital moments, leading to magnetic anisotropy.

Predicted electric polarization exceeds experimental values.

Abstract

Ca3CoMnO6 is composed of CoMnO6 chains made up of face-sharing CoO6 trigonal prisms and MnO6 octahedra. The structural, magnetic, and ferroelectric properties of this compound were investigated on the basis of density functional theory calculations. Ca3CoMnO6 is found to undergo a Jahn-Teller distortion associated with the CoO6 trigonal prisms containing high-spin Co2+ (d7) ions, which removes the C3 rotational symmetry and hence uniaxial magnetism. However, the Jahn-Teller distortion is not strong enough to fully quench the orbital moment of the high-spin Co2+ ions thereby leading to an electronic state with substantial magnetic anisotropy. The Jahn-Teller distorted Ca3CoMnO6 in the magnetic ground state with up-up-down-down spin arrangement is predicted to have electric polarizations much greater than experimentally observed. Implications of the discrepancy between theory and experiment were discussed.