Level spectroscopy in a two-dimensional quantum magnet: Linearly dispersing spinons at the deconfined quantum critical point
Level spectroscopy in a two-dimensional quantum magnet: Linearly dispersing spinons at the deconfined quantum critical point
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DOI：
10.1103/physrevb.94.144416
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发表时间：
2016-07
影响因子：
3.7
通讯作者：
H. Suwa;Arnab Sen;A. Sandvik
中科院分区：
文献类型：
--
作者：
H. Suwa;Arnab Sen;A. Sandvik
本文以$J\text{\ensuremath{-}}Q$模型为例，研究了二维量子自旋系统中分离反铁磁相和键固相的“定义”临界点处的激发能级结构。从量子蒙特卡罗模拟中得到的虚时间相关函数中提取不同自旋$(S)$和动量$(\mathbf{k})$扇区的能隙。我们找到了强有力的定量证据，证明在$\mathbf{k}=(0,0),(\ensuremath{\pi},0),(0,\ensuremath{\pi})$和$(\ensuremath{\pi},\ensuremath{\pi})$和$(\ensuremath{\pi})$处具有无间隙点的定义线性分散自旋子，这是由这些点周围的双自旋激振（$S=0$和$S=1$状态）推断出来的。我们还观察到临界点和有序相内部的单重态和三重态激发之间的对偶性，以支持增强的对称性，可能是SO(5)。
We study the level structure of excitations at the ``deconfined'' critical point separating antiferromagnetic and valence-bond-solid phases in two-dimensional quantum spin systems using the $J\text{\ensuremath{-}}Q$ model as an example. Energy gaps in different spin $(S)$ and momentum $(\mathbf{k})$ sectors are extracted from imaginary-time correlation functions obtained in quantum Monte Carlo simulations. We find strong quantitative evidence for deconfined linearly dispersing spinons with gapless points at $\mathbf{k}=(0,0),(\ensuremath{\pi},0),(0,\ensuremath{\pi})$, and $(\ensuremath{\pi},\ensuremath{\pi})$, as inferred from two-spinon excitations ($S=0$ and $S=1$ states) around these points. We also observe a duality between singlet and triplet excitations at the critical point and inside the ordered phases, in support of an enhanced symmetry, possibly SO(5).