Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 53: Frustrated Magnets - Strong Spin-Orbit Coupling (joint session TT/MA)

TT 53.3: Talk

Thursday, April 4, 2019, 10:00–10:15, Theater

Thermodynamic evidence for proximity to the Kitaev QSL in A₂IrO₃ (A = Na, Li) — •Kavita Mehlawat^1,2, A Thamizhavel³, and Yogesh Singh¹ — ¹Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, Mohali 140306, India. — ²Leibniz Institute for Solid State and Materials Research IFW Dresden, 01069 Dresden, Germany — ³Department of Condensed Matter Physics and Material Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India

The honeycomb lattice iridates A₂IrO₃ (A = Na, Li) are candidates for the realization of the Kitaev-Heisenberg model although their proximity to Kitaev’s quantum Spin-Liquid (QSL) is still debated. We report on heat capacity C and entropy S_mag for A₂IrO₃ (A = Na, Li) in the temperature range 0.075 K≤ T ≤ 155 K [1]. We find a two-peak structure for the magnetic heat capacity C_mag for both materials and S_mag shows a plateau between the peaks with a value close to 1/2Rln2. These features signal the fractionalization of spins into Majorana Fermions close to Kitaev’s QSL as predicted recently [2, 3]. These results provide the first thermodynamic evidence for the proximity of A₂IrO₃ to the Kitaev QSL [1].

Financial support: Hallwachs-Röntgen Postdoc Program, UGC-CSIR India.
K. Mehlawat, A. Thamizhavel, and Y. Singh, Phy. Rev. B 95, 144406 (2017)
J. Nasu, M. Udagawa, and Y. Motome, Phys. Rev. B 92 115122 (2015)
Y. Yamaji, T. Suzuki, T. Yamada, S. I. Suga, N. Kawashima, and M. Imada, Phys. Rev. B 93, 174425 (2016)