Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: Theory 2

TT 34.2: Talk

Thursday, September 8, 2022, 15:15–15:30, H23

Huge enhancement of the thermal conductivity in the Tomonaga-Luttinger-liquid region of YbAlO₃ — •Parisa Mokhtari^1,2, Ulrike Stockert¹, and Elena Hassinger^1,2 — ¹Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany — ²Physics Department, Technical University of Munich, Garching, Germany

In 2019, Wu et al. found the typical excitation spectrum of the spinons in the Q-1D material YbAlO₃ via neutron scattering at 1 K. YbAlO₃ exhibit AFM (J_c=2.3 K) and FM (J_ab=0.8 K) exchange interaction along and perpendicular to the chain direction, respectively [1, 2]. In zero field, a 3D AFM order is established at 0.88 K. For fields along a, perpendicular to the chain, this order is suppressed and replaced by an IC-AFM state, until the FI-FM state occurs for B >1.5 T.

It is an open question, if magnetic excitations in this material carry heat, and how they interact with phonons. Hence, we investigate the low-T κ of YbAlO₃ down to 30 mK in fields up to 4 T. The phase diagram is successfully reproduced with pronounced anomalies in both T and B sweeps. A clear additional anomaly in the field dependence at low T confirms a crossover within the IC phase, which was suggested before based only on a tiny plateau appearing in the magnetisation. We find a large variation of the κ throughout the phase diagram indicating strong magneto-elastic coupling. In addition, a substantial enhancement of kappa is observed in the proposed TLL region.

[1] L. S. Wu et al., Nat. Commun. 10, 698 (2019)

[2] L. S. Wu et al., Phys. Rev. B 99, 195117 (2019)