Ground-state phase diagram of the triangular lattice Hubbard model by the density-matrix renormalization group method
Ground-state phase diagram of the triangular lattice Hubbard model by the density-matrix renormalization group method
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DOI：
10.1103/physrevb.96.205130
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发表时间：
2016-06
影响因子：
3.7
通讯作者：
T. Shirakawa;T. Tohyama;J. Kokalj;S. Sota;S. Yunoki
中科院分区：
文献类型：
--
作者：
T. Shirakawa;T. Tohyama;J. Kokalj;S. Sota;S. Yunoki
利用二维密度矩阵重整化群方法研究了半填充三角晶格上Hubbard模型的基态相图。计算结果表明，随着排斥Hubbard相互作用U的增加，在Uc_1 = 7.55 t和Uc_2 = 9.65 t（t为跳跃积分）处，双占有率存在两个不连续性，表明存在由一级跃迁分离的三相. 0 Uc ~ 2的物理量不存在任何奇异性，表现出三子格的特征，这与在强耦合极限下实现的Neel有序态是相容的。当Uc 1 < U <Uc 2时，对外加钉扎磁场的响应与金属相相当，但自旋相关长度相对较大，既没有价键，也没有手性磁序，表明其具有类似于无带隙自旋液体的顺磁性。计算还发现，对关联函数随U的增大而单调减小，因此在中间相不可能出现超导性。
Two-dimensional density-matrix renormalization group method is employed to examine the ground state phase diagram of the Hubbard model on the triangular lattice at half filling. The calculation reveals two discontinuities in the double occupancy with increasing the repulsive Hubbard interaction U at Uc1 = 7.55 t and Uc2 = 9.65 t (t being the hopping integral), indicating that there are three phases separated by first order transitions. The absence of any singularity in physical quantities for 0 Uc2 exhibits a three sublattice feature, which is compatible with the Neel ordered state realized in the strong coupling limit. For Uc1 < U < Uc2, a response to the applied pinning magnetic field is comparable to that in the metallic phase but a relatively large spin correlation length is found with neither valence bond nor chiral magnetic order, suggesting a paramagnetic nature which resembles gapless spin liquid. The calculation also finds that the pair- ing correlation function monotonically decreases with increasing U and thus the superconductivity is unlikely in the intermediate phase.