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arXiv 1312.1111cond-mat.str-el
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高磁场下的正方形量子海森堡反铁磁体:定域磁振子范例及其他

The square-kagome quantum Heisenberg antiferromagnet at high magnetic fields: The localized-magnon paradigm and beyond

Oleg Derzhko, Johannes Richter, Olesia Krupnitska, Taras Krokhmalskii

摘要:

本文研究了自旋为1/2的反铁磁海森伯模型在最低磁振子带几乎无色散的二维正方形格子上的性质。对于一般的交换耦合几何形状,我们阐述了低能量的有效哈密顿出现在高磁场。描述初始受抑量子自旋模型的低能自由度的有效模型是在$z$取向磁场中的(未受抑)正方晶格自旋1/2 $XXZ$模型。对于有效模型,我们进行了量子蒙特卡罗模拟,讨论了高磁场下方形量子海森堡反铁磁体的低温性质。我们特别注意磁场驱动的Berezinskiii-Kosterlitz无磁相变,发生在低温下。

英文摘要:

We consider the spin-1/2 antiferromagnetic Heisenberg model on the two-dimensional square-kagome lattice with almost dispersionless lowest magnon band. For a general exchange coupling geometry we elaborate low-energy effective Hamiltonians which emerge at high magnetic fields. The effective model to describe the low-energy degrees of freedom of the initial frustrated quantum spin model is the (unfrustrated) square-lattice spin-1/2 $XXZ$ model in a $z$-aligned magnetic field. For the effective model we perform quantum Monte Carlo simulations to discuss the low-temperature properties of the square-kagome quantum Heisenberg antiferromagnet at high magnetic fields. We pay special attention to a magnetic-field driven Berezinskii-Kosterlitz-Thouless phase transition which occurs at low temperatures.

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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