SKM 2021 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 3: Focus Session: Entanglement as a Probe for Correlated Quantum Matter
TT 3.4: Talk
Monday, September 27, 2021, 15:15–15:30, H6
Robustness of the thermal Hall effect close to half-quantization in a field-induced spin liquid state — •Jan Bruin1, Ralf Claus1, Yosuke Matsumoto1, Nobuyuki Kurita2, Hidekazu Tanaka2, and Hidenori Takagi1,3 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 2Department of Physics, Tokyo Institute of Technology, Tokyo, Japan — 3Department of Physics, The University of Tokyo, Bunkyo, Tokyo, Japan
Thermal signatures of fractionalized excitations are a fingerprint of quantum spin liquids (QSLs). In the Jeff=1/2 honeycomb magnet α-RuCl3, a QSL state emerges upon applying an in-plane magnetic field H|| greater than the critical field HC2 ≈ 7 T along the a-axis, where the thermal Hall conductivity (kXY/T) was reported to take on the half-quantized value kHQ/T. This finding was discussed as a signature of an emergent Majorana edge mode predicted for the Kitaev QSL. The H||- and T-range of the half-quantized signal and its relevance to a Majorana edge mode are, however, still under debate.
Here we present a comprehensive study of kXY/T in α-RuCl3 with H|| up to 13 T and T down to 250 mK, which reveals the presence of an extended region of the phase diagram with kXY/T ≈ kHQ/T above HC2. The results are in support of a topological state with a half-quantized kXY/T and suggest an interplay with crossovers or weak phase transitions beyond HC2 in α-RuCl3.