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arXiv 0911.2379cond-mat.quant-gas
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三维自旋和硬核玻色子模型的超固相

Supersolid phase of Three-dimensional spin and hardcore-boson models

H. T. Ueda, K. Totsuka

摘要:

本文研究了体心立方晶格上三维自旋和硬核玻色-哈伯德模型的固相和超固相的稳定性。为了研究量子效应对SS相稳定性的影响,我们采用自旋波玻色子模型来模拟固体中引入的空位,并采用凝聚玻色子之间的相互作用作为判据.低能有效相互作用的排斥性质是二阶固体-SS转变的必要条件,当满足此条件时,通常预期SS相。在计算有效相互作用时,我们使用了半经典(即大S)和伊辛极限的展开,并结合了阶梯近似。量子涨落的影响主要取决于半填充时固相和超流相的能量。作为对4 He的应用,我们研究了Liu和Fisher给出的拟合参数集附近的参数区域。对于这个参数集,在1/S中的二阶量子涨落使固相不稳定,这在平均场论中被认为是稳定的。

英文摘要:

We study the stability of solid- and supersolid (SS) phases of a three-dimensional spin- and a hardcore-Bose-Hubbard models on a body-centered cubic lattice. To see the quantum effects on the stability of the SS phase, we model the vacancies (interstitials) introduced in the solid, which are believed responsible for the appearance of the SS phase, by spinwave bosons and adopt the interaction between the condensed bosons as a criterion. A repulsive nature of the low-energy effective interaction is the necessary condition for a second-order solid-SS transition and, when this condition is met, normally the SS phase is expected. In calculating the effective interaction, we use expansions from the semiclassical- (i.e. large-S) and the Ising limit combined with the ladder approximation. The impact of quantum fluctuations crucially depends on the energy of the solid phase and that of the superfluid phase at half filling. As an application to 4He, we study the parameter region in the vicinity of the fitting parameter set given by Liu and Fisher. For this parameters set, quantum fluctuations at the second order in 1/S destabilize the solid phase, which is supposed to be stable within the mean field theory.

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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