Dynamical Signatures of Quasiparticle Interactions in Quantum Spin Chains
Dynamical Signatures of Quasiparticle Interactions in Quantum Spin Chains
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量子自旋链中准粒子相互作用的动力学特征
DOI：
10.1103/physrevlett.125.187201
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发表时间：
2020
影响因子：
8.6
通讯作者：
Starykh, Oleg A.
中科院分区：
文献类型：
--
作者：
Keselman, Anna;Balents, Leon;Starykh, Oleg A.
研究了在纵向塞曼场作用下反铁磁自旋链的横向动力学磁化率。在低磁化制度中的无间隙阶段，我们表明，在小动量的两个分支的激发之间的自旋之间的边缘无关的背散射相互作用创建一个非零的间隙。我们进一步证明了这种差距如何变化时，引入第二个邻居反铁磁相互作用，消失在一个非相互作用的“自旋气体”的限制。在高磁化强度区，当塞曼场接近饱和值时，我们发现在横向磁化率中出现了双磁振子束缚态。这种束缚态特征推广了可积情况下Bethe近似解中弦态的特征。我们的结果是基于数值准确，无偏矩阵产品状态技术以及解析近似。
We study the transverse dynamical susceptibility of an antiferromagnetic spin-chain in the presence of a longitudinal Zeeman field. In the low magnetization regime in the gapless phase, we show that the marginally irrelevant backscattering interaction between the spinons creates a nonzero gap between two branches of excitations at small momentum. We further demonstrate how this gap varies upon introducing a second neighbor antiferromagnetic interaction, vanishing in the limit of a noninteracting “spinon gas.” In the high magnetization regime, as the Zeeman field approaches the saturation value, we uncover the appearance of two-magnon bound states in the transverse susceptibility. This bound state feature generalizes the one arising from string states in the Bethe ansatz solution of the integrable case. Our results are based on numerically accurate, unbiased matrix-product-state techniques as well as analytic approximations.