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arXiv 0906.4818cond-mat.stat-mech
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中间统计自旋波

Intermediate-statistics spin waves

Wu-Sheng Dai, Mi Xie

摘要:

本文证明了海森堡磁系统的元激发自旋波服从一种最大占据数n有限的中间统计。我们构造了磁振子量子化自旋波服从的中间统计量的算符实现,然后根据磁振子的产生算符和湮灭算符构造了角动量代数的相应中间统计量实现.换句话说,而不是Holstein-Primakoff表示,玻色子表示受到约束的占用数,我们提出了一个中间统计表示没有约束。在这种实现中,最大占有数自然体现在创造和湮灭算子的对易关系中,而Holstein-Primakoff表示是一种玻色子算子关系,对占有数有一个额外的手推限制。我们推导了磁振子的中间统计分布函数。在此基础上,我们计算了铁磁和反铁磁自旋波的色散关系。讨论了磁振子所服从的中间统计量与另外两种重要的中间统计量--Haldane-Wu统计量和任意子的分数统计量之间的关系。我们还比较了中间统计自旋波的谱与一维s = 1/2海森堡模型的精确解,这是通过Bethe的方法获得的。对于铁磁体,我们考虑了磁振子之间的相互作用(四次贡献),次近邻相互作用和偶极相互作用的贡献,以与实验进行比较。

英文摘要:

In this paper, we show that spin waves, the elementary excitation of the Heisenberg magnetic system, obey a kind of intermediate statistics with a finite maximum occupation number n. We construct an operator realization for the intermediate statistics obeyed by magnons, the quantized spin waves, and then construct a corresponding intermediate-statistics realization for the angular momentum algebra in terms of the creation and annihilation operators of the magnons. In other words, instead of the Holstein-Primakoff representation, a bosonic representation subject to a constraint on the occupation number, we present an intermediate-statistics representation with no constraints. In this realization, the maximum occupation number is naturally embodied in the commutation relation of creation and annihilation operators, while the Holstein-Primakoff representation is a bosonic operator relation with an additional putting-in-by-hand restriction on the occupation number. We deduce the intermediate-statistics distribution function for magnons. On the basis of these results, we calculate the dispersion relations for ferromagnetic and antiferromagnetic spin waves. The relations between the intermediate statistics that magnons obey and the other two important kinds of intermediate statistics, Haldane-Wu statistics and the fractional statistics of anyons, are discussed. We also compare the spectrum of the intermediate-statistics spin wave with the exact solution of the one-dimensional s = 1/2 Heisenberg model, which is obtained by the Bethe ansatz method. For ferromagnets, we take the contributions from the interaction between magnons (the quartic contribution), the next-to-nearest neighbor interaction, and the dipolar interaction into account for comparison with the experiment.

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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