Modified spin-wave theory for the S = 1 frustrated antiferromagnetic Heisenberg chain
Modified spin-wave theory for the S = 1 frustrated antiferromagnetic Heisenberg chain
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DOI：
10.1140/epjb/e2007-00082-x
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发表时间：
2007-03
期刊：
影响因子：
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通讯作者：
G. M. Rocha-Filho;A. Pires;M. E. Gouvea
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文献类型：
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作者：
G. M. Rocha-Filho;A. Pires;M. E. Gouvea
利用修正自旋波理论（MSWT）研究了具有反铁磁近邻（nn）和次近邻（nnn）相互作用的一维各向同性自旋-1海森堡磁体。用nnn相互作用常数与nnn相互作用常数之比来定义几个j值，得到了基态能量和单重态-三重态能隙。我们还比较了目前在文献中发现的两种不同的实现MSWT的方法，并表明，尽管在每个过程中要求解的方程之间存在显着差异，但两者给出的结果都是等效的，除了每种处理中可获得的j的最大值jmax的预测值。在此，我们认为jmaxis与第一类失序点有关。结果表明，当j≤jmax时，基态和间隙能随j的增大而增大，与前人的数值结果一致。
We study the one-dimensional isotropic spin-1 Heisenberg magnet with antiferromagnetic nearest-neighbor (nn) and next-nearest-neighbor (nnn) interactions by using the modified spin wave theory (MSWT). The ground state energy and the singlet-triplet energy gap are obtained for several values of j, defined as the ratio of the nnn interaction constant to the nn one. We also compare two different ways of implementing the MSWT currently found in the literature, and show that, despite the remarkable differences between the equations to be solved in each procedure, the results given by both are equivalent, except for the predicted value of the jmax, the maximum value of j accessible in each treatment. Here, we suggest that jmaxis related to the disorder point of the first kind. Our results show that the ground state and the gap energies increase with j, for j ≤jmax, in accordance to previous numerical results.