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arXiv 1009.0840cond-mat.str-el
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磁场中弱耦合反铁磁自旋1/2阶梯的静力学和动力学

Statics and dynamics of weakly coupled antiferromagnetic spin-1/2 ladders in a magnetic field

Pierre Bouillot, Corinna Kollath, Andreas M. Läuchli, Mikhail Zvonarev, Benedikt Thielemann, Christian Rüegg, Edmond Orignac, Roberta Citro, Martin Klanjsek, Cl… 展开作者

Pierre Bouillot, Corinna Kollath, Andreas M. Läuchli, Mikhail Zvonarev, Benedikt Thielemann, Christian Rüegg, Edmond Orignac, Roberta Citro, Martin Klanjsek, Claude Berthier, Mladen Horvatic, Thierry Giamarchi

摘要:

本文研究了磁场中弱耦合的自旋1/2阶梯。这项工作的动机是最近的实验化合物(C5 H12 N)2CuBr 4(BPCB)。我们使用数值和分析相结合的方法,特别是密度矩阵重整化群(DMRG)技术,探索这样的系统的相图和激发光谱。我们给出了详细的结果的磁化强度和比热的温度依赖性,和磁场依赖的核磁共振(NMR)弛豫率的单梯。对于耦合梯,用平均场或量子蒙特卡罗方法处理梯间弱耦合,计算了三重态凝聚的转变温度和相应的反铁磁序参量.现有的实验测量进行了讨论,并与我们的理论结果进行比较。此外,我们计算,使用含时DMRG,一个单一的自旋梯的动力学关联。我们的结果可以直接描述高能量中子的非弹性散射截面。我们专注于磁场的光谱的演变,并比较他们的行为为不同的耦合。使用不同的分析方法,如映射到自旋链,Luttinger液体(LL)或t-J模型上的光谱的特征进行解释。对于这些测量存在的参数值,我们比较我们的结果的化合物BPCB的非弹性中子散射实验,并找到很好的协议。我们对光谱的高能量部分进行了额外的预测,这些预测在未来的实验中可能是可测试的。

英文摘要:

We investigate weakly coupled spin-1/2 ladders in a magnetic field. The work is motivated by recent experiments on the compound (C5H12N)2CuBr4 (BPCB). We use a combination of numerical and analytical methods, in particular the density matrix renormalization group (DMRG) technique, to explore the phase diagram and the excitation spectra of such a system. We give detailed results on the temperature dependence of the magnetization and the specific heat, and the magnetic field dependence of the nuclear magnetic resonance (NMR) relaxation rate of single ladders. For coupled ladders, treating the weak interladder coupling within a mean-field or quantum Monte Carlo approach, we compute the transition temperature of triplet condensation and its corresponding antiferromagnetic order parameter. Existing experimental measurements are discussed and compared to our theoretical results. Furthermore we compute, using time dependent DMRG, the dynamical correlations of a single spin ladder. Our results allow to directly describe the inelastic neutron scattering cross section up to high energies. We focus on the evolution of the spectra with the magnetic field and compare their behavior for different couplings. The characteristic features of the spectra are interpreted using different analytical approaches such as the mapping onto a spin chain, a Luttinger liquid (LL) or onto a t-J model. For values of parameters for which such measurements exist, we compare our results to inelastic neutron scattering experiments on the compound BPCB and find excellent agreement. We make additional predictions for the high energy part of the spectrum that are potentially testable in future experiments.

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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