Quantum spin liquid emerging in two-dimensional correlated Dirac fermions
Quantum spin liquid emerging in two-dimensional correlated Dirac fermions
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DOI：
10.1038/nature08942
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发表时间：
2010-04-08
期刊：
影响因子：
64.8
通讯作者：
Muramatsu, A.
中科院分区：
文献类型：
--
作者：
Meng, Z. Y.;Lang, T. C.;Muramatsu, A.
在足够低的温度下，凝聚态物质体系趋向于有序发展。这种行为的一个明显例外是量子自旋液体，其中量子涨落阻止了向有序状态的过渡，直至最低温度。现在已经在一些二维有机化合物中对这种状态进行了初步观察，然而量子自旋液体在与实验相关的微观二维模型中仍然难以捉摸。在这里，我们通过蜂窝晶格（例如石墨烯中实现的结构）上相关费米子的大规模量子蒙特卡罗模拟显示，量子自旋液体出现在由无质量狄拉克费米子和反铁磁有序莫特绝缘体描述的状态之间。这种意想不到的量子无序状态被发现是一种短程共振的价键液体，类似于高温超导体：因此，在我们的系统中，通过掺杂产生非常规超导性的可能性出现了。我们预测这个模型系统的实验实现使用超冷原子，或在蜂窝晶格中排列的IV族元素。
At sufficiently low temperatures, condensed-matter systems tend to develop order. A notable exception to this behaviour is the case of quantum spin liquids, in which quantum fluctuations prevent a transition to an ordered state down to the lowest temperatures. There have now been tentative observations of such states in some two-dimensional organic compounds, yet quantum spin liquids remain elusive in microscopic two-dimensional models that are relevant to experiments. Here we show, by means of large-scale quantum Monte Carlo simulations of correlated fermions on a honeycomb lattice (a structure realized in, for example, graphene), that a quantum spin liquid emerges between the state described by massless Dirac fermions and an antiferromagnetically ordered Mott insulator. This unexpected quantum-disordered state is found to be a short-range resonating valence-bond liquid, akin to the one proposed for high-temperature superconductors: the possibility of unconventional superconductivity through doping therefore arises in our system. We foresee the experimental realization of this model system using ultra-cold atoms, or group IV elements arranged in honeycomb lattices.