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arXiv 2007.03717cond-mat.str-el
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磁场中的Heisenberg-Kitaev模型:$1/S$展开

Heisenberg-Kitaev model in a magnetic field: $1/S$ expansion

Pedro M. Cônsoli, Lukas Janssen, Matthias Vojta, Eric C. Andrade

摘要:

Kitaev的自旋- $1/2$蜂窝状自旋-液体模型的精确解引发了对具有键依赖Kitaev相互作用的莫特绝缘体的强烈搜索,其中$\mathrm{Na}_{2}\mathrm{IrO}_{3}$和$α-\mathrm{RuCl}_{3}$是主要的例子。随后,已经提出Kitaev相互作用的自旋- $1$和自旋- $3/2$类似物也可以发生在具有强自旋-轨道耦合的材料中。作为描述这些Kitaev材料的最小模型,我们在一致的$1/S$展开中研究了Heisenberg-Kitaev哈密顿量,其中$S$是自旋大小。我们提出了一个全面的研究这个模型中存在的外部磁场沿两个不同的方向,[001]和[111],其中一个复杂的经典相图已被报道。在这两种设置中,我们采用自旋波理论在一些有序的阶段计算在下一个领先的顺序在$1/S$的相边界,并表明量子校正大幅修改经典相图。更广泛地说,我们的工作提供了一个一致的路线,调查领先的量子修正自旋模型,打破自旋旋转对称性。

英文摘要:

The exact solution of Kitaev's spin-$1/2$ honeycomb spin-liquid model has sparked an intense search for Mott insulators hosting bond-dependent Kitaev interactions, of which $\mathrm{Na}_{2}\mathrm{IrO}_{3}$ and $α-\mathrm{RuCl}_{3}$ are prime examples. Subsequently, it has been proposed that also spin-$1$ and spin-$3/2$ analogs of Kitaev interactions may occur in materials with strong spin-orbit coupling. As a minimal model to describe these Kitaev materials, we study the Heisenberg-Kitaev Hamiltonian in a consistent $1/S$ expansion, with $S$ being the spin size. We present a comprehensive study of this model in the presence of an external magnetic field applied along two different directions, [001] and [111], for which an intricate classical phase diagram has been reported. In both settings, we employ spin-wave theory in a number of ordered phases to compute phase boundaries at the next-to-leading order in $1/S$ and show that quantum corrections substantially modify the classical phase diagram. More broadly, our work presents a consistent route to investigate the leading quantum corrections in spin models that break spin-rotational symmetry.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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