The formation of a non-magnetic state for the d6 electronic system

TL;DR

This paper demonstrates how crystal-field and spin-orbit interactions in a d6 system can produce a non-magnetic ground state with significant implications for materials like LaCoO3, explaining their magnetic behavior.

Contribution

It introduces a model showing the formation of a non-magnetic singlet ground state in d6 systems considering spin-orbit and trigonal distortions, aligning with experimental observations.

Findings

Non-magnetic singlet ground state can arise in d6 systems due to crystal-field and spin-orbit interactions.

The energy level scheme includes non-magnetic ground and magnetic excited states at 11 and 70 meV.

Magnetic susceptibility deviates from Curie law due to second-order CEF interactions.

Abstract

It has been shown that the crystal-field interactions can produce a non- magnetic singlet ground state for the highly-correlated d6 system situated in the quasi-octahedral crystal field (CEF) surrounding provided the spin-orbit interactions are correctly taking into account. The spin-orbit interactions in combination with the trigonal distortion of the cubic CEF interactions produce a peculiar energy level scheme with a non-magnetic ground state and highly- magnetic excited states at 11 and 70 meV. The calculated temperature dependence of the magnetic susceptibility exhibits very substantial departure from the Curie law that is due to second-order CEF interactions. The present considerations can be applied to Co3+ and Fe2+- ion compounds. The derived electronic and magnetic properties mimic very much those found experimentally for LaCoO3.