Quantum criticality, lines of fixed points, and phase separation in doped two-dimensional quantum dimer models
Quantum criticality, lines of fixed points, and phase separation in doped two-dimensional quantum dimer models
复制标题
掺杂二维量子二聚体模型中的量子临界性、不动点线和相分离
DOI：
10.1103/physrevb.76.134514
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发表时间：
2006
影响因子：
3.7
通讯作者：
E. Fradkin
中科院分区：
文献类型：
--
作者：
S. Papanikolaou;Erik Luijten;E. Fradkin
本文研究了一类正方晶格上的掺杂量子二聚体模型的相图，其基态波函数的振幅具有经典掺杂二聚体模型的吉布斯权的形式。在这个二聚体模型中，平行相邻的二聚体有吸引力的相互作用，而相邻的空穴要么不相互作用，要么有排斥力的相互作用。我们通过分析方法和Monte Carlo模拟研究了该系统的行为。在零掺杂，我们确认存在一个Kosterlitz无相变从量子临界相到柱状相。在低的空穴密度，我们发现一个二聚体孔液相和柱状相，分离的相边界，这是一条线的临界点与不同的指数。我们证明，这条线结束于多临界点的过渡成为一阶和系统相分离。的一阶过渡共存曲线示出成为不稳定的更复杂的非均匀相在直接的空穴-空穴相互作用的存在下。我们还使用变分方法来确定在二聚体孔流体相的低密度波动的频谱。
We study phase diagrams of a class of doped quantum dimer models on the square lattice with ground-state wave functions whose amplitudes have the form of the Gibbs weights of a classical doped dimer model. In this dimer model, parallel neighboring dimers have attractive interactions, whereas neighboring holes either do not interact or have a repulsive interaction. We investigate the behavior of this system via analytic methods and by Monte Carlo simulations. At zero doping, we confirm the existence of a Kosterlitz-Thouless transition from a quantum critical phase to a columnar phase. At low hole densities, we find a dimer-hole liquid phase and a columnar phase, separated by a phase boundary which is a line of critical points with varying exponents. We demonstrate that this line ends at a multicritical point where the transition becomes first order and the system phase separates. The first-order transition coexistence curve is shown to become unstable with respect to more complex inhomogeneous phases in the presence of direct hole-hole interactions. We also use a variational approach to determine the spectrum of low-lying density fluctuations in the dimer-hole fluid phase.