Superconductivity and a Mott Transition in a Hubbard Model on an Anisotropic Triangular Lattice

Abstract

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 the Mott transition and superconductivity arising in κ-BEDT-TTF_2X. 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 band width, for a wide range of t'/t. This transition is not directly connected to magnetism. Robust d-wave superconductivity appears in a restricted parameter range: immediately below U_c and moderate strength of frustration (0.4\lsim t'/t\lsim 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.

15 pages, 17 figures, submitted to J. Phys. Soc. Jpn

References in corpus (4)

• Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor kappa-(ET)2Cu2(CN)3
• Comparison of the phase diagram of the half-filled layered organic superconductors with the phase diagram of the RVB theory of the Hubbard-Heisenberg model
• Universality Classes of Metal-Insulator Transitions in Strongly Correlated Electron Systems and Mechanism of High-Temperature Superconductivity
• Magnetism and superconductivity of strongly correlated electrons on the triangular lattice

Cited by in corpus (13)

• From high temperature supercondutivity to quantum spin liquid: progress in strong correlation physics
• Variational Monte Carlo Method Combined with Quantum-Number Projection and Multi-Variable Optimization
• Mott Transitions and d-wave Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice with Geometric Frustration
• Finite temperature Mott transition in Hubbard model on anisotropic triangular lattice
• Exact diagonalization study of Mott transition in the Hubbard model on an anisotropic triangular lattice
• Absence of superconductivity in the half-filled band Hubbard model on the anisotropic triangular lattice
• Symmetry of the superconducting order parameter in frustrated systems determined by the spatial anisotropy of spin correlations
• Quantum critical transition from charge-ordered to superconducting state in the triangular lattice negative-U extended Hubbard model
• Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets
• Half-filled Hubbard Model on a Bethe lattice with next-nearest neighbor hopping
• Mott transition and superconductivity in the strongly correlated organic superconductor $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2]$Br
• Variational Monte Carlo analysis of the Hubbard model with a confining potential: one-dimensional fermionic optical lattice systems
• Doublon-Holon Binding Effects on Mott Transitions in Two-Dimensional Bose Hubbard Model