标题： 通过改进的能级光谱方法在Shastry-Sutherland模型中检测到量子自旋液相 显示英文标题

标题： Quantum spin liquid phase in the Shastry-Sutherland model detected by an improved level spectroscopic method

摘要： 我们通过周期性边界条件下的簇的精确对角化来研究自旋-$1/2$二维Shastry-Sutherland自旋模型。 我们开发了一种改进的能级光谱技术，利用不同量子数状态之间的能量间隙。 一些相对（复合）间隙的交叉点比通常仅相对于基态定义的间隙具有更弱的有限尺寸漂移，从而即使使用小簇也能精确确定量子临界点。 我们的结果支持一种自旋液相存在于已知的晶格单态和反铁磁基态之间的图像，相边界与最近的密度矩阵重正交化群研究几乎完美一致，其中使用了更大的圆柱形晶格 [J. Yang 等, Phys. Rev. B{\bf 105}, L060409 (2022)]。 使用复合低能间隙来减少标度修正的方法在量子临界现象的数值研究中可能有广泛的应用。 显示英文摘要

摘要： We study the spin-$1/2$ two-dimensional Shastry-Sutherland spin model by exact diagonalization of clusters with periodic boundary conditions. We develop an improved level spectroscopic technique using energy gaps between states with different quantum numbers. The crossing points of some of the relative (composite) gaps have much weaker finite-size drifts than the normally used gaps defined only with respect to the ground state, thus allowing precise determination of quantum critical points even with small clusters. Our results support the picture of a spin liquid phase intervening between the well known plaquette-singlet and antiferromagnetic ground states, with phase boundaries in almost perfect agreement with a recent density matrix renormalization group study, where much larger cylindrical lattices were used [J. Yang et al., Phys. Rev. B {\bf 105}, L060409 (2022)]. The method of using composite low-energy gaps to reduce scaling corrections has potentially broad applications in numerical studies of quantum critical phenomena.