Extended Bose-Hubbard model on a honeycomb lattice
Extended Bose-Hubbard model on a honeycomb lattice
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蜂窝晶格上的扩展 Bose-Hubbard 模型
DOI：
10.1103/physrevb.75.214509
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发表时间：
2007-06-01
影响因子：
3.7
通讯作者：
Yu, Yue
中科院分区：
文献类型：
--
作者：
Gan, Jing Yu;Wen, Yu Chuan;Yu, Yue
利用大规模量子Monte Carlo方法研究了二维蜂窝晶格上的扩展玻色-哈伯德模型。我们提出了硬核和软核玻色子的基态相图。对于硬核情况，ρ =1/2固体与超流之间的转变是一级的，并且超固态对于相分离是不稳定的。对于软核情况，由于多重占位的存在，当1/2 < 1时，出现稳定的粒子诱导超固态（SS-p）相。从rho=1/2的固体到SS-p相的转变是二级的，超流密度标度为rho（s），类似于rho-1/2。在ρ =1/2处，SS-p相具有与固体相同的对角阶。随着化学势的进一步增加，SS-p相变成固体，其中两个玻色子通过一级跃迁占据一个子晶格的每个位置。我们还计算了在Heisenberg点的rho=1/2固体和超流之间的过渡的临界指数的硬核的情况下。我们发现的动力学临界指数z=0.15，这是小于较小的晶格上获得的结果。这表明z在热力学极限接近零，因此即使在海森堡点，跃迁也是一级的。
We study the extended Bose-Hubbard model on a two-dimensional honeycomb lattice by using large-scale quantum Monte Carlo simulations. We present the ground-state phase diagrams for both the hard-core and the soft-core bosons. For the hard-core case, the transition between the rho=1/2 solid and the superfluid is first order, and the supersolid state is unstable toward phase separation. For the soft-core case, due to the presence of multiple occupation, a stable particle-induced supersolid (SS-p) phase emerges when 1/2 < 1. The transition from the solid at rho=1/2 to the SS-p phase is second order with the superfluid density scaling as rho(s)similar to rho-1/2. The SS-p phase has the same diagonal order as the solid at rho=1/2. As the chemical potential increases further, the SS-p phase turns into a solid where two bosons occupy each site of one sublattice through a first-order transition. We also calculate the critical exponents of the transition between the rho=1/2 solid and superfluid at the Heisenberg point for the hard-core case. We find the dynamical critical exponent z=0.15, which is smaller than results obtained on smaller lattices. This indicates that z approaches zero in the thermodynamic limit, and thus the transition is also first order even at the Heisenberg point.