Dresden 2020 – wissenschaftliches Programm
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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.