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TT: Fachverband Tiefe Temperaturen
TT 46: Frustrated Magnets: Spin Liquids
TT 46.5: Talk
Thursday, March 30, 2023, 10:30–10:45, HSZ 201
Anisotropic phonon-spin scattering in the quantum spin liquid canidate NaYbS2 — •Matthias Gillig1,2, Xiaochen Hong1,3, Ellen Häußler2, Philipp Schlender2, Thomas Doert2, Bernd Büchner1,2, and Christian Hess1,3 — 1IFW Dresden — 2TU Dresden — 3Bergische Universität Wuppertal
A perfect triangular spin lattice and absence of long-range magnetic order down to T=260 mK make the delafossite material NaYbS2 a prime candidate to host a quantum spin liquid ground state. We present the results of heat transport experiments on NaYbS2 in the low-temperature limit (T < 1 K), where the in-plane thermal conductivity κab shows a peculiar temperature dependence mimicking a potential residual linear term that decays below 500 mK. Application of in-plane magnetic field drastically enhances the thermal conductivity until it saturates in the field polarized limit. This behavior hints at phonon dominated heat transport with very strong magnetic phonon scattering where magnetic field suppresses the phonon scattering off spin fluctuations and the phonon thermal conductivity recovers at high field. In the field-dependence of κ broad features appear that indicate possible field-induced phase transitions in the magnetic system. Within this framework no clear evidence for magnetic heat transport due to spin excitations is observed. The investigation of the anisotropy of κ reveals that the phonon-spin scattering is strongly anisotropic and the out-of-plane coupling of phonons to spin excitations is weakened.