Department of Physics and Astronomy, University of California, Irvine, California 92697, USA.
Physics Department, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2013 Dec 20;111(25):257201. doi: 10.1103/PhysRevLett.111.257201. Epub 2013 Dec 16.
Using the density matrix renormalization group on wide cylinders, we study the phase diagram of the spin-1/2 XY model on the honeycomb lattice, with first-neighbor (J1=1) and frustrating second-neighbor (J2>0) interactions. For the intermediate frustration regime 0.22≲J2≲0.36, we find a surprising antiferromagnetic Ising phase, with ordered moments pointing along the z axis, despite the absence of any S(z)S(z) interactions in the Hamiltonian. Surrounding this phase as a function of J2 are antiferromagnetic phases with the moments pointing in the x-y plane for small J2 and a close competition between an x-y plane magnetic collinear phase and a dimer phase for large values of J2. We do not find any spin-liquid phases in this model.
我们使用宽圆柱上的密度矩阵重整化群研究了带有最近邻（J1=1）和竞争次近邻（J2>0）相互作用的 honeycomb 晶格上的自旋为 1/2 的 XY 模型的相图。对于中间竞争强度范围 0.22≲J2≲0.36，我们发现了一个令人惊讶的反铁磁 Ising 相，尽管哈密顿量中没有任何 S(z)S(z)相互作用，但有序矩指向 z 轴。在这个相的周围，随着 J2 的变化，出现了反铁磁相，其中矩指向小 J2 的 x-y 平面，而在大 J2 时，x-y 平面磁共线相和二聚相之间存在激烈竞争。在这个模型中，我们没有发现任何自旋液体相。
