Cascade of Spin Liquids in a Bilayer Triangular-lattice Antiferromagnet Rb_2Co_2(SeO_3)_3

TL;DR

This paper reports the discovery of a cascade of classical spin liquids in a bilayer triangular lattice antiferromagnet under high magnetic fields, revealing new pathways to explore spin liquid states.

Contribution

It demonstrates a field-controlled route to spin liquids in Rb₂Co₂(SeO₃)₃, including a candidate quantum spin liquid at a fractional magnetization plateau.

Findings

Cascade of classical spin liquids characterized by degenerate local spin configurations.

Residual entropy of 1/2(1-M/M_s)Rln2 per mole in the spin liquid states.

Identification of a 5/6-plateau state as a candidate quantum spin liquid.

Abstract

In frustrated Ising magnets, classical spin liquids (CSLs) with macroscopic ground-state degeneracy can survive against conventional magnetic order, as exemplified by systems on triangular, kagome and pyrochlore lattices at zero field. Here we report the discovery of a high-field route toward spin liquids in a bilayer triangular lattice antiferromagnet, Rb$_2$Co$_2$(SeO$_3$)$_3$. We demonstrate that a cascade of CSLs -- characterized by doubly degenerate one-up-one-down local spin configurations and a residual entropy of 1/2(1-M/M_s)Rln2 per mole -- emerges through field-controlled dilution of Ising dimers. Owing to the interplay of intra- and inter-layer interactions, these CSLs are further stabilized by lattice symmetry breaking at fractional magnetization plateaus. Such field-induced spin liquids can be understood as a consequence of generalized ice rules, analogous to those governing in pyrochlore antiferromagnets. In particular, the 5/6-plateau state is a candidate quantum spin liquid. Our results thereby establish a new pathway for exploring diverse spin liquid states across both classical and quantum regimes.