摘要翻译：
用重整化群理论研究了各向异性XXZ自旋1/2海森堡链。计算了铁磁区和反铁磁区的温度范围和各向异性范围内的比热和最近邻自旋-自旋关联，得到了全局描述和定量结果。在各向异性条件下，我们得到了反铁磁自旋-液体自旋波速和类似铁磁激发谱隙，显示了自旋波与自旋子的交叉。在反铁磁XXZ链中，面内相互作用S_i^x S_j^x+S_i^y S_j^y在较高温度下诱导出面外S_i^z分量的反铁磁关联，在铁磁XXZ链中，在较低温度下主要诱导出反铁磁关联，在XY链中，在所有温度下，面内相互作用S_i^x S_j^x+S_i^y S_j^y诱导出反铁磁关联。我们发现反铁磁的XXZ链中也有反效应：反铁磁的s_i^z、s_j^z相互作用在s_i^xy分量中产生关联。作为另一个纯量子效应，(i)在反铁磁体中，比热峰的值对各向异性不敏感，比热峰的温度由各向同性（海森堡）降低，引入任一类型（伊辛或XY）各向异性；(ii)完全相反，在铁磁体中，比热峰的值和温度随各向异性的任何一种而增加。
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英文标题：
《Excitation Spectrum Gap and Spin-Wave Stiffness of XXZ Heisenberg
  Chains: Global Renormalization-Group Calculation》
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作者：
Ozan S. Sariyer, A. Nihat Berker, and Michael Hinczewski
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最新提交年份：
2008
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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英文摘要：
  The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the antiferromagnetic XXZ chain: an antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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PDF链接：
https://arxiv.org/pdf/704.1064