Superconductivity and a Mott Transition in a Hubbard Model on an Anisotropic Triangular Lattice(Condensed matter: electronic structure and electrical, magnetic, and optical properties)
Superconductivity and a Mott Transition in a Hubbard Model on an Anisotropic Triangular Lattice(Condensed matter: electronic structure and electrical, magnetic, and optical properties)
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DOI：
10.1143/jpsj.75.074707
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发表时间：
2006-02
影响因子：
1.7
通讯作者：
Tsutomu Watanabe;H. Yokoyama;Yukio Tanaka;J. Inoue
中科院分区：
文献类型：
--
作者：
Tsutomu Watanabe;H. Yokoyama;Yukio Tanaka;J. Inoue
用优化变分Monte Carlo方法研究了各向异性三角晶格上的半满带Hubbard模型（两个键向为t，另一个键向为t '），讨论了κ-（BEDT-TTF）2 X中的Mott跃迁和超导电性.采用含双光子-holon结合因子的波函数，我们揭示了在宽的t '/ t范围内，一阶Mott（导体-绝缘体）跃迁发生在U = Uc处，约为带宽的1/2。这种转变与磁性没有直接联系。强d波超导性出现在一个有限的参数范围内：直接低于Uc和中等强度的挫折（\（0.4 {\lesssim} t '/t {\lesssim} 0.7\）），其中短程反铁磁关联充分发展，但没有达到长程秩序。实验的相关性也进行了讨论。
A half-filled-band Hubbard model on an anisotropic triangular lattice ( t in two bond directions and t ' in the other) is studied using an optimization variational Monte Carlo method, to consider a Mott transition and superconductivity arising in κ-(BEDT-TTF) 2 X. Adopting wave functions with doublon–holon binding factors, we reveal that a first-order Mott (conductor-to-nonmagnetic insulator) transition takes place at U = U c , approximately of the bandwidth, for a wide t '/ t range. This transition is not directly connected to magnetism. Robust d -wave superconductivity appears in a restricted parameter range: immediately below U c and the moderate strength of frustration (\(0.4 {\lesssim} t'/t {\lesssim} 0.7\)), where short-range antiferromagnetic correlation sufficiently develops but does not come to a long-range order. The relevance to experiments is also discussed.