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Magnetic field induced topological transitions and thermal conductivity in a generalized Kitaev model
Physical Review B ( IF 3.7 ) Pub Date : 2022-06-27 , DOI: 10.1103/physrevb.105.245142
Heqiu Li, Yong Baek Kim, Hae-Young Kee

Recent experiments on Kitaev spin liquid candidate materials reported nonmonotonic behavior of thermal conductivity as a function of magnetic field, which lead to conflicting interpretations of its origin. Motivated by this development, we study the magnetic field dependence of thermal conductivity of a generalized Kitaev model, which allows the phase transitions between different flux sectors as a function of the magnetic field. The thermal conductivity due to Majorana fermions shows dip-bump structures as the magnetic field increases, which is caused by either the transitions between different flux sectors of Kitaev spin liquids or the topological transitions that change the Majorana Chern number within the same flux sector. It is shown that the change of Chern number is closely related to the four-Majorana-fermion interaction induced by the magnetic field. The nonmonotonic behavior in thermal conductivity emerges at finite temperature, and it becomes weaker when temperature decreases toward zero. Our model provides a generic mechanism for the Kitaev spin liquids to develop nonmonotonic magnetic-field dependence of thermal conductivity while the comparison to realistic materials remains an open question for future investigation.

中文翻译:

广义 Kitaev 模型中的磁场诱导拓扑跃迁和热导率

最近对 Kitaev 自旋液体候选材料的实验报告了热导率随磁场变化的非单调行为,这导致对其起源的解释相互矛盾。受此发展的启发,我们研究了广义 Kitaev 模型的热导率的磁场依赖性,该模型允许不同通量扇区之间的相变作为磁场的函数。由马约拉纳费米子引起的热导率随着磁场的增加显示出凹凸结构,这是由基塔耶夫自旋液体的不同通量扇区之间的跃迁或改变同一通量扇区内的马约拉纳陈数的拓扑跃迁引起的。结果表明陈数的变化与磁场引起的四马约拉纳-费米子相互作用密切相关。热导率的非单调行为在有限温度下出现,当温度降低到零时变得更弱。我们的模型为 Kitaev 自旋液体提供了一种通用机制,以发展热导率的非单调磁场依赖性,而与实际材料的比较仍然是未来研究的悬而未决的问题。
更新日期:2022-06-27
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