Second generation of triangular spin-liquid candidates

Recent years have seen an increased interest in studying the spin-liquid physics of triangular antiferromagnets. On the experimental side, YbMgGaO₄ was the first and very successful shot, but its spin-liquid-like ground state is strongly influenced by the Mg/Ga disorder and associated randomness. In this talk, I will review the results on the second generation of spin-liquid candidates that were recently introduced as disorder-free triangular antiferromagnets. I will show that, despite the initial claims, Na₂BaCo(PO₄)₂ is magnetically long-range-ordered below 150 mK and reveals subtle randomness effects caused by structural dynamics. An extensive mapping of the temperature-field phase diagram suggests a close proximity of this compound to the nearest-neighbor XXZ triangular antiferromagnet. Further on, I will present thermodynamic properties of the AYbX₂ (A = Na, K and X = S, Se) rocksalt-type compounds where a competition between first- and second-neighbor interactions on the triangular lattice may stabilize the spin-liquid state. I will discuss the nature of low-energy excitations in these materials as well as their possible quantum critical behavior.