Rare-earth chalcogenides: A large family of triangular lattice spin liquid candidate

TL;DR

This paper introduces a large family of rare-earth chalcogenides with triangular lattice structures, which are promising candidates for quantum spin liquids due to their stable magnetic properties and structural simplicity.

Contribution

The study synthesizes and characterizes a new family of rare-earth chalcogenides sharing the same structure as YbMgGaO$_4$, providing a cleaner platform for quantum spin liquid research.

Findings

No structural or magnetic transition down to 50mK.

Family compounds have simple structure and chemical formula.

Rich diversity allows tunable properties.

Abstract

Frustrated quantum magnets are expected to host many exotic quantum spin states like quantum spin liquid (QSL), and have attracted numerous interest in modern condensed matter physics. The discovery of the triangular lattice spin liquid candidate YbMgGaO$_4$ stimulated an increasing attention on the rare-earth-based frustrated magnets with strong spin-orbit coupling. Here we report the synthesis and characterization of a large family of rare-earth chalcogenides AReCh$_2$ (A = alkali or monovalent ions, Re = rare earth, Ch = O, S, Se). The family compounds share the same structure (R$\bar{3}$m) as YbMgGaO$_4$, and antiferromagnetically coupled rare-earth ions form perfect triangular layers that are well separated along the $c$-axis. Specific heat and magnetic susceptibility measurements on NaYbO$_2$, NaYbS$_2$ and NaYbSe$_2$ single crystals and polycrystals, reveal no structural or magnetic transition down to 50mK. The family, having the simplest structure and chemical formula among the known QSL candidates, removes the issue on possible exchange disorders in YbMgGaO$_4$. More excitingly, the rich diversity of the family members allows tunable charge gaps, variable exchange coupling, and many other advantages. This makes the family an ideal platform for fundamental research of QSLs and its promising applications.