Thermodynamics of a gauge-frustrated Kitaev spin liquid
Thermodynamics of a gauge-frustrated Kitaev spin liquid
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DOI：
10.1103/physrevresearch.1.032011
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发表时间：
2019-11-01
影响因子：
4.2
通讯作者：
Trebst, S.
中科院分区：
文献类型：
--
作者：
Eschmann, T.;Mishchenko, P. A.;Trebst, S.
二维和三维Kitaev磁体是典型的受抑量子自旋系统，其中原始自旋自由度分解为Majorana费米子和Z（2）规范场-一种纯粹的局部现象，在由键方向相互作用强度设定的温度标度下显示为热力学交叉。对于传统的Kitaev磁体，低温热力学揭示了Z（2）规范场有序化和系统进入自旋液体基态的第二个转变。在这里，我们讨论一个明确的例子，超越了这个范式的规范场-Z（2）规范场被发现是受几何挫折，热序转变被抑制，并产生广泛的剩余熵。在量子体系的深处，在相互作用强度每密耳一个的温度下，规范场和马约拉纳费米子之间的微妙相互作用提升了规范扇区的简并度，导致马约拉纳金属的形成。我们讨论了从大规模、无符号量子蒙特卡罗模拟中获得的该物理学的热力学特征。
Two- and three-dimensional Kitaev magnets are prototypical frustrated quantum spin systems, in which the original spin degrees of freedom fractionalize into Majorana fermions and a Z(2) gauge field-a purely local phenomenon that reveals itself as a thermodynamic crossover at a temperature scale set by the strength of the bond-directional interactions. For conventional Kitaev magnets, the low-temperature thermodynamics reveals a second transition at which the Z(2) gauge field orders and the system enters a spin-liquid ground state. Here, we discuss an explicit example that goes beyond this paradigmatic scenario-the Z(2) gauge field is found to be subject to geometric frustration, the thermal ordering transition is suppressed, and an extensive residual entropy arises. Deep in the quantum regime, at temperatures of the order of one per mil of the interaction strength, the degeneracy in the gauge sector is lifted by a subtle interplay between the gauge field and the Majorana fermions, resulting in the formation of a Majorana metal. We discuss the thermodynamic signatures of this physics obtained from large-scale, sign-free quantum Monte Carlo simulations.