Variational study of quantum fluctuations in anisotropic antiferromagnets
Variational study of quantum fluctuations in anisotropic antiferromagnets
复制标题
各向异性反铁磁体中量子涨落的变分研究
DOI：
10.1088/0953-8984/5/44/026
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
B. Oleś
中科院分区：
文献类型：
--
作者：
A. Oleś;B. Oleś
将Bartkowski(1972)提出的处理量子反铁磁体基态的变分波函数推广到任意自旋。我们利用局域团簇展开导出了能量和磁化强度的基本方程。在大自旋S极限或晶格维D极限下，确定了波函数的前级修正。正方形晶格上的海森堡S=1/2反铁磁体的基态能量E_0=-0.3340J证实了波函数的良好性质。我们给出了两平面系统、三维SC和BCC晶格以及三维各向异性海森堡模型的结果。结果发现，两平面系统中的量子涨落已经更接近于三维而不是二维反铁磁体，而后者的弱平面间耦合几乎不影响平面内的最近邻自旋关联。
The variational wave function proposed by Bartkowski (1972) to treat the ground state of a quantum antiferromagnet is generalized to arbitrary spin. We derive the fundamental equations of this method for the energy and magnetization by using a local cluster expansion. The leading order corrections to the wave function in the limit of either large spin S or lattice dimension D are identified. The good quality of the wave function is confirmed by the ground state energy of E0 = -0.3340J obtained for the Heisenberg S = 1/2 antiferromagnet on the square lattice. We present results obtained for the system of two planes and for three-dimensional SC and BCC lattices, as well as for the three-dimensional anisotropic Heisenberg model. It is found that the quantum fluctuations in a two-plane system are already closer to a three-dimensional than to a two-dimensional antiferromagnet while a weak interplane coupling in the latter case hardly influences the nearest-neighbour spin correlations within the planes.