Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 24: Frustrated Magnets - Spin Liquids 1 (joint session TT/MA)

TT 24.2: Vortrag

Dienstag, 17. März 2020, 09:45–10:00, HSZ 304

Magnetic properties of the NaYbO₂ and KYbO₂ triangular antiferromagnets — •Franziska Grußler, Sebastian Bachus, Philipp Gegenwart, and Alexander A. Tsirlin — Centerfor Electronic Correlations and Magnetism, University of Augsburg, Augsburg, Germany

NaYbO₂ and KYbO₂ 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 these triangular antiferromagnets including their structural characterization and thermodynamic properties in the milli-K temperature range. Both NaYbO₂ and KYbO₂ reveal magnetic interactions of about 4 K and no signs of magnetic order in zero field, but undergo field-induced magnetic order that in the Na case occurs between 3 T and 8 T. By studying specific heat of NaYbO₂ 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. In zero field, no simple power-law behavior can be observed, but the data clearly deviated from an activated behavior expected for a gapped ground state. Our observations establish gapless nature of the spin-liquid phase of triangular antiferromagnets.