论文标题
耦合霍尔丹链的表面临界行为
Surface critical behaviors of coupled Haldane chains
论文作者
论文摘要
在相应的经典临界点中排除了(2+1) - 维量子临界点的特殊表面跃迁。到目前为止,这种行为的机制仅在二聚体的海森伯格模型中发现。 To illuminate the role of symmetry protected topological (SPT) phase in inducing such nonordinary behaviors, we study a system on a two-dimensional square lattice consisted by interacting spin-1 Haldane chains, which has a genuine SPT phase--the Haldane phase--at weak interchain interactions and a quantum critical point belonging to the classical 3D O(3) universality class to the Néel phase.与之前研究的模型不同,当前模型中没有二聚化。沿链方向切割系统或垂直于链方向露出两个不同的表面。使用公正的量子蒙特卡洛模拟,我们发现两种不同类型的表面在块状临界点显示出完全不同的表面临界行为,这是由SPT阶段的不同表面状态产生的。对于沿链方向表面表面的系统,表面临界行为是散装3D O(3)临界点的普通类型,而对于垂直于链方向的表面,表面临界行为是非凡的,与在Dimerized Heisenberg模型中发现的特殊过渡一致。我们的数值结果表明,在间隙SPT相位的无间隙表面状态以及临界点的无间隙模式是导致非凡过渡的纯量子场景。
The special surface transition at (2+1)-dimensional quantum critical point is precluded in corresponding classical critical point. The mechanism of such behavior which is only found in dimerized Heisenberg models so far is still under debate. To illuminate the role of symmetry protected topological (SPT) phase in inducing such nonordinary behaviors, we study a system on a two-dimensional square lattice consisted by interacting spin-1 Haldane chains, which has a genuine SPT phase--the Haldane phase--at weak interchain interactions and a quantum critical point belonging to the classical 3D O(3) universality class to the Néel phase. Different from models studied previously, there is no dimerization in the current model. Cutting the system along the chain direction or perpendicular to the chain direction exposes two different surfaces. Using unbiased quantum Monte Carlo simulations, we find that the two different types of surface show completely different surface critical behaviors at the bulk critical point, resulted from different surface states in the SPT phase. For the system with surfaces along the chain direction, the surface critical behavior is of ordinary type of the bulk 3D O(3) critical point, while for the surfaces perpendicular to the chain direction, the surface critical behavior is nonordinary, consistent with special transitions found in dimerized Heisenberg models. Our numerical results demonstrate that the gapless surface state in the gapped SPT phase together with the gapless mode of critical point is a pure quantum scenario that leads to the nonordinary transition.