Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA and Institute for Nuclear Research of Russian Academy of Sciences, 117312 Moscow, Russia.
Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA and Russian Research Center "Kurchatov Institute," 123182 Moscow, Russia.
Phys Rev Lett. 2013 Feb 15;110(7):070601. doi: 10.1103/PhysRevLett.110.070601. Epub 2013 Feb 11.
We demonstrate, by considering the triangular lattice spin-1/2 Heisenberg model, that Monte Carlo sampling of skeleton Feynman diagrams within the fermionization framework offers a universal first-principles tool for strongly correlated lattice quantum systems. We observe the fermionic sign blessing--cancellation of higher order diagrams leading to a finite convergence radius of the series. We calculate the magnetic susceptibility of the triangular-lattice quantum antiferromagnet in the correlated paramagnet regime and reveal a surprisingly accurate microscopic correspondence with its classical counterpart at all accessible temperatures. The extrapolation of the observed relation to zero temperature suggests the absence of the magnetic order in the ground state. We critically examine the implications of this unusual scenario.
我们通过考虑三角晶格上的自旋-1/2 海森堡模型，证明了在费米子化框架内对骨架费曼图进行蒙特卡罗抽样为强关联晶格量子系统提供了通用的第一性原理工具。我们观察到了费米子符号 blessing——高阶图的抵消导致级数的有限收敛半径。我们计算了关联顺磁区中三角晶格量子反铁磁体的磁化率，并在所有可及的温度下揭示了与经典对应物惊人精确的微观对应关系。观察到的关系外推到零温度表明基态不存在磁有序。我们批判性地检查了这种异常情况的影响。
