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Finite-momentum energy dynamics in a Kitaev magnet
Physical Review B ( IF 3.7 ) Pub Date : 2021-09-24 , DOI: 10.1103/physrevb.104.104424
Alexandros Metavitsiadis , Wolfram Brenig

We study the energy-density dynamics at finite momentum of the two-dimensional Kitaev spin model on the honeycomb lattice. Due to fractionalization of magnetic moments, the energy relaxation occurs through mobile Majorana matter, coupled to a static Z2 gauge field. At finite temperatures, the Z2 flux excitations act as a thermally induced disorder, which strongly affects the energy dynamics. We show that sufficiently far above the flux proliferation temperature, but not yet in the high-temperature classical regime, disordered gauge configurations modify the coherent low-temperature energy-density dynamics into a form which is almost diffusive, with a diffusion kernel that is nearly momentum independent, but which remains retarded, primarily due to the presence of two distinct relaxation channels of particle-hole and particle-particle nature. Relations to the thermal conductivity are clarified. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge configuration and a mean-field treatment of thermal gauge fluctuations, valid above the flux proliferation temperature.

中文翻译:

Kitaev 磁体中的有限动量能量动力学

我们研究了蜂窝晶格上二维 Kitaev 自旋模型的有限动量下的能量密度动力学。由于磁矩的分馏,能量弛豫通过移动的马约拉纳物质发生,耦合到静态Z2规领域。在有限温度下,Z2通量激发作为一种热诱导紊乱,强烈影响能量动力学。我们表明,在通量扩散温度之上足够远,但尚未在高温经典状态下,无序规范配置将相干的低温能量密度动力学修改为几乎是扩散的形式,扩散核几乎是动量独立,但仍然延迟,主要是由于存在两个不同的粒子-空穴和粒子-粒子性质的弛豫通道。阐明了与热导率的关系。我们的分析基于低温均匀规配置中的补充计算和热规波动的平均场处理,在通量扩散温度以上有效。
更新日期:2021-09-24
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