arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1606.03294cond-mat.str-elcond-mat.mes-hall
收藏

自旋为1/2的XXZ链在横场中的动力学结构因子

Dynamic structure factor of the spin-1/2 XXZ chain in a transverse field

Benedikt Bruognolo, Andreas Weichselbaum, Jan von Delft, Markus Garst

摘要:

在横场中具有易平面各向异性的自旋$\frac{1}{2}$ XXZ链很好地描述了材料${\rm Cs_2CoCl_4}$在宽的温度和场范围内的热力学性质,包括靠近自旋翻转伊辛量子相变的区域。为了与这种化合物的预期非弹性中子散射实验进行比较,我们提出了一个广泛的数值研究的结果,其动态结构因子$\mathcal{S}^{αβ}(k,ω)$使用矩阵产品状态(MPS)技术。接近临界,相关器$\mathcal{S}^{xx}$的动态部分纵向的应用领域是不相干的,并拥有一个小的总重量的基态已经接近饱和。横向相关器$\mathcal{S}^{zz}$,另一方面,是占主导地位的相干单粒子激发与额外的光谱重量在较高的能量,我们暂时归因于一个排斥绑定粒子对。随着温度的升高,后者迅速消失,谱权重反而在单粒子能量上方接近零波矢。在技术层面上,我们比较了实时演化的数值效率,在目前的背景下,基于MPS的切比雪夫展开,发现这两种方法产生的结果质量相似,数值成本相当。

英文摘要:

The spin-$\frac{1}{2}$ XXZ chain with easy-plane anisotropy in a transverse field describes well the thermodynamic properties of the material ${\rm Cs_2CoCl_4}$ in a wide range of temperatures and fields including the region close to the spin-flop Ising quantum phase transition. For a comparison with prospective inelastic neutron scattering experiments on this compound, we present results of an extensive numerical study of its dynamic structure factor $\mathcal{S}^{αβ}(k,ω)$ using matrix-product-state (MPS) techniques. Close to criticality, the dynamic part of the correlator $\mathcal{S}^{xx}$ longitudinal to the applied field is incoherent and possesses a small total weight as the ground state is already close to saturation. The transverse correlator $\mathcal{S}^{zz}$, on the other hand, is dominated by a coherent single-particle excitation with additional spectral weight at higher energies that we tentatively attribute to a repulsively bound pair of particles. With increasing temperature, the latter quickly fades and spectral weight instead accumulates close to zero wavevector just above the single-particle energy. On a technical level, we compare the numerical efficiency of real-time evolution to an MPS-based Chebyshev expansion in the present context, finding that both methods yield results of similar quality at comparable numerical costs.

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。

↑