Department of Physics, University of Toronto, Toronto, Ontario, Canada M5S 1A7.
Phys Rev Lett. 2010 Jan 8;104(1):015301. doi: 10.1103/PhysRevLett.104.015301. Epub 2010 Jan 4.
We study the spin-1/2 XXZ model on the triangular lattice with a nearest neighbor antiferromagnetic Ising coupling J(z) > 0 and unfrustrated (J(perpendicular) < 0) or frustrated (J(perpendicular) >0) kinetic terms in a zero magnetic field. Incorporating long-range Jastrow correlations over a mean-field spin state, we obtain the variational phase diagram of this model on large lattices for arbitrary J(z) and either sign of J(perpendicular). For J(perpendicular) < 0, we find a square root(3) x square root(3) supersolid for J(z)/J(perpendicular)| approximately > 4.7, in excellent agreement with quantum Monte Carlo data. For J(perpendicular) > 0, a distinct square root(3) x square root(3) supersolid is found to emerge for J(z)/J(perpendicular) > or = 1. Both supersolids exhibit a spontaneous density deviation from half-filling. At J(z)/J(perpendicular) = infinity, the crystalline order parameters of these two supersolids are nearly identical, consistent with exact results.
我们研究了三角晶格上的自旋-1/2 XXZ 模型，具有最近邻反铁磁伊辛耦合 J(z) > 0 和非受挫（J(perpendicular) < 0）或受挫（J(perpendicular) >0）的无磁场动力学项。在平均场自旋态上加入长程 Jastrow 关联，我们得到了该模型在大晶格上的变分相图，对于任意的 J(z)和 J(perpendicular)的任意符号。对于 J(perpendicular) < 0，我们发现对于 J(z)/J(perpendicular)|约大于 4.7，存在一个平方根(3) x 平方根(3)超固体，与量子蒙特卡罗数据非常吻合。对于 J(perpendicular) > 0，发现了一个明显的平方根(3) x 平方根(3)超固体，对于 J(z)/J(perpendicular)大于等于 1。这两种超固体都表现出自发的密度偏离半满。在 J(z)/J(perpendicular) = 无穷大时，这两种超固体的晶体有序参数几乎相同，与精确结果一致。
