Magnetic behavior of curium dioxide with non-magnetic ground state

TL;DR

This study investigates the unexpected magnetic behavior of CmO$_2$ with a non-magnetic ground state by numerically analyzing magnetic susceptibility using a seven-orbital Anderson model considering spin-orbit coupling.

Contribution

It provides a novel explanation for magnetic behavior in CmO$_2$ through numerical evaluation of excited states influenced by crystal electric fields.

Findings

Magnetic excited states exist with lower excitation energy than expected.

Crystalline electric field effects enable magnetic behavior despite a non-magnetic ground state.

The model explains observed magnetic susceptibility in CmO$_2$.

Abstract

In order to understand magnetic behavior observed in CmO$_2$ with non-magnetic ground state, we numerically evaluate magnetic susceptibility on the basis of a seven-orbital Anderson model with spin-orbit coupling. Naively we do not expect magnetic behavior in CmO$_2$, since Cm is considered to be tetravalent ion with six $5f$ electrons and the ground state is characterized by $J$=0, where $J$ is total angular momentum. However, there exists magnetic excited state and the excitation energy is smaller than the value of the Land\'e interval rule due to the effect of crystalline electric field potential. Then, we open a way to explain magnetic behavior in CmO$_2$.