SKM 2021 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 3: Focus Session: Entanglement as a Probe for Correlated Quantum Matter

TT 3.6: Vortrag

Montag, 27. September 2021, 15:45–16:00, H6

Comparative study of the triangular spin-liquid candidates NaYbO₂, KYbO₂ and KYbS₂ — •Franziska Grußler, Sebastian Bachus, Noah Winterhalter-Stocker, Philipp Gegenwart, and Alexander Tsirlin — Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg, Germany

Spin liquid is an entangled state of matter. NaYbO₂, KYbO₂ and KYbS₂ feature the same space group R3m as the spin-liquid candidate YbMgGaO₄ but evade structural disorder pertinent to that compound. We report a comparative study of the polycrystalline NaYbO₂ and KYbO₂ and single crystalline KYbS₂ including their structural characterization and thermodynamic properties in the milli-K temperature range. The compounds reveal the reduction in magnetic couplings upon replacing Na by K and the enhanced easy-plane anisotropy upon replacing O by S. They show no signs of magnetic order in zero field, but undergo field-induced magnetic order. For KYbS₂ a detailed B-T phase diagram is deduced from heat capacity, dilatometry and magnetization measurements for B∥c. By studying specific heat of NaYbO₂ and KYbS₂ at milli-K temperatures, we conclude that between 0.5 T and 2 T, within the putative spin-liquid phase, magnetic specific heat follows quadratic behavior expected for the gapless Dirac spin liquid. Our observations establish gapless nature of the spin-liquid phase of triangular antiferromagnets but show strong similarities to 120-degree ordered triangular antiferromagnets when B∥c is applied.