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arXiv 1004.0848cond-mat.str-elcond-mat.stat-mech
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量子自旋1/2 XX金刚石链的磁性:Jordan-Wigner方法

Magnetic properties of the quantum spin-1/2 XX diamond chain: The Jordan-Wigner approach

Taras Verkholyak, Jozef Strecka, Michal Jascur, Johannes Richter

摘要:

利用Jordan-Wigner变换研究了自旋为1/2的量子$XX$模型在金刚石链上的磁性.一般来说,这个量子自旋系统的哈密顿量可以表示为在规范场的存在下的无自旋费米子和不同的规范不变的方式分配的自旋费米子变换被认为是。此外,我们分析了自由费米子链的一般性质,其中所有的规范项被忽略,并讨论了它们与量子自旋系统的相关性。费米子哈密顿量中的相互作用项的考虑依赖于在固定适当的规范之后的Hartree-Fock过程。最后,我们讨论了该量子自旋模型在零温度以及非零温度下的磁性,并通过与有限(最多36个自旋)链的精确对角化方法的结果进行比较,分析了所用近似的有效性。除了$m=1/3$平台之外,磁化曲线的最显著特征是对于某些值的令人沮丧的垂直键存在的中间场处的跳跃。

英文摘要:

The Jordan-Wigner transformation is applied to study magnetic properties of the quantum spin-1/2 $XX$ model on the diamond chain. Generally, the Hamiltonian of this quantum spin system can be represented in terms of spinless fermions in the presence of a gauge field and different gauge-invariant ways of assigning the spin-fermion transformation are considered. Additionally, we analyze general properties of a free-fermion chain, where all gauge terms are neglected and discuss their relevance for the quantum spin system. A consideration of interaction terms in the fermionic Hamiltonian rests upon the Hartree-Fock procedure after fixing the appropriate gauge. Finally, we discuss the magnetic properties of this quantum spin model at zero as well as non-zero temperatures and analyze the validity of the approximation used through a comparison with the results of the exact diagonalization method for finite (up to 36 spins) chains. Besides the $m=1/3$ plateau the most prominent feature of the magnetization curve is a jump at intermediate field present for certain values of the frustrating vertical bond.

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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