Integer vs. half-integer spin on an approximate honeycomb lattice

TL;DR

This study compares magnetic behaviors of two rare earth compounds on an approximate honeycomb lattice, revealing distinct magnetic orderings linked to their integer or half-integer spins, with implications for quantum spin liquid research.

Contribution

It provides the first direct comparison of integer versus half-integer spins on an approximate honeycomb lattice in rare earth compounds.

Findings

Nd$_2$S$_5$Sn orders antiferromagnetically at 2.5 K.

Pr$_2$S$_5$Sn shows no magnetic order above 0.41 K.

Pr$_2$S$_5$Sn may be close to a quantum spin liquid state.

Abstract

Recent interest in honeycomb lattice materials has focused on their potential to host quantum spin liquid (QSL) states. Variations in bond angles and spin allow a range of interesting behaviors on this lattice, from the predicted QSL ground state of the Kitaev model to exotic magnetic orders. Here we report the physical properties of two compounds with rare earths on an approximate honeycomb lattice. The isostructural compounds Nd$_2$S$_5$Sn (J = $\frac{9}{2}$) and Pr$_2$S$_5$Sn (J = 4) permit a direct comparison of half-integer versus integer spins on this lattice. We find strikingly different magnetic properties for the two compounds. Nd$_2$S$_5$Sn orders antiferromagnetically at T$_N$ $\approx$ 2.5 K, and undergoes several magnetic transitions to other ordered states under applied field. Pr$_2$S$_5$Sn displays no magnetic ordering transition above T = 0.41 K, and may be proximate to a spin liquid state.