Atomic-scale description of the paramagnetic susceptibility of non-magnetic Ba$_2$YMoO$_6$

TL;DR

This paper provides a detailed theoretical explanation of the temperature-dependent paramagnetic susceptibility of Ba$_2$YMoO$_6$, attributing it to atomic-scale electronic structure effects and explaining the nonmagnetic ground state observed experimentally.

Contribution

It offers a novel atomic-scale theoretical model that accurately reproduces the susceptibility behavior of Ba$_2$YMoO$_6$ across all temperatures, highlighting the role of crystal-field and spin-orbit interactions.

Findings

Successful theoretical description of susceptibility over entire temperature range

Identification of Mo$^{5+}$ ions as the main magnetic species

Explanation of nonmagnetic ground state down to 50 mK

Abstract

We succeeded in remarkably nice theoretical description of the temperature dependence of the paramagnetic susceptibility of Ba$_2$YMoO$_6$ in the whole temperature range as originating from the atomic-scale discrete electronic structure of Mo$^{5+}$ ions in the 4d$^1$ configuration resulting from crystal-field and spin-orbit interactions. A strong violation of the Curie-Weiss law and a nonmagnetic state of BYMo experimentally-observed down to 50 mK is caused by the dramatical reduction of the Mo-ion magnetic moment. The quantitative reproduction of $\chi$(T) proves that almost all Mo ions are in the Mo$^{5+}$ state over the whole temperature range.