Properties of an algebraic spin liquid on the kagome lattice
Properties of an algebraic spin liquid on the kagome lattice
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DOI：
10.1103/physrevb.77.224413
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发表时间：
2008-06-01
影响因子：
3.7
通讯作者：
Wen, Xiao-Gang
中科院分区：
文献类型：
--
作者：
Hermele, Michael;Ran, Ying;Wen, Xiao-Gang
在最近的工作中，我们认为一个特殊的代数自旋液体（ASL）可能是基态的S = 1/2 kagome晶格海森堡反铁磁体。此外，这种状态，它缺乏自旋间隙，是有吸引力的光在最近的实验对herbertsmithite [ZnCu3（OH）（6）Cl-2]。在这里，我们使用低能有效场论和Gutzwiller投影的费米子自旋波函数来更详细地研究这个ASL的性质。我们确定了ASL的竞争级，它们是具有缓慢衰减的幂律相关性的可观测量-其中我们发现了位于布里渊区M点的一组磁序，熟悉的q = 0磁序态，"黑斯廷斯"价键固体（VBS）态，和矢量自旋手性排序的模式对应于一个的Dzyaloshinskiii-Moriya（DM）的相互作用项中存在于herbertsmithite。识别这些订单中的一些需要理解的量子数的磁性磁算符在ASL。我们讨论了在实验中的磁性和VBS竞争订单的检测。虽然我们主要集中在一个干净的系统没有DM相互作用，我们认为小DM相互作用的影响，并认为，令人惊讶的是，它会导致自发破缺的时间反演对称性（DM相互作用，保持XY自旋旋转对称性，也有XY磁序）。我们对投影波函数的分析提供了对表征ASL所有低能激发的"费米速度" v（F）的估计，这使我们能够估计比热，这与实验相比是有利的。我们还研究了自旋和键相关的投影波函数，并比较这些结果与有效场理论。虽然有效场论中的自旋关联和波函数似乎匹配得相当好（尽管不完全），但键关联更令人困惑。最后，我们讨论的实验在赫氏石，并作出几个预测。
In recent work, we argued that a particular algebraic spin liquid (ASL) may be the ground state of the S=1/2 kagome lattice Heisenberg antiferromagnet. Furthermore, this state, which lacks a spin gap, is appealing in light of recent experiments on herbertsmithite [ZnCu3(OH)(6)Cl-2]. Here, we study the properties of this ASL in more detail using both the low-energy effective field theory and Gutzwiller-projected wave functions of fermionic spinons. We identify the competing orders of the ASL, which are observables having slowly decaying power-law correlations-among them we find a set of magnetic orders lying at the M points of the Brillouin zone, the familiar q=0 magnetic ordered state, the "Hastings" valence-bond solid (VBS) state, and a pattern of vector spin-chirality ordering corresponding to one of the Dzyaloshinskii-Moriya (DM) interaction terms present in herbertsmithite. Identification of some of these orders requires an understanding of the quantum numbers of magnetic monopole operators in the ASL. We discuss the detection of the magnetic and VBS competing orders in experiments. While we primarily focus on a clean system without DM interaction, we consider the effects of small DM interaction and argue that, surprisingly, it leads to spontaneously broken time-reversal symmetry (for DM interaction that preserves XY spin rotation symmetry, there is also XY magnetic order). Our analysis of the projected wave function provides an estimate of the "Fermi velocity" v(F) that characterizes all low-energy excitations of the ASL-this allows us to estimate the specific heat, which compares favorably with experiments. We also study the spin and bond correlations of the projected wave function and compare these results with those of the effective field theory. While the spin correlations in the effective field theory and wave function seem to match rather well (although not completely), the bond correlations are more puzzling. We conclude with a discussion of experiments in herbertsmithite and make several predictions.