$\kappa -(BEDT-TTF{)}_{2}X$ organic crystals: superconducting versus antiferromagnetic instabilities in an anisotropic triangular lattice Hubbard model

Abstract

A Hubbard model at half-filling on an anisotropic triangular lattice has been proposed as the minimal model to describe conducting layers of $\kappa -(BEDT-TTF{)}_{2}X$ organic materials. The model interpolates between the square lattice and decoupled chains. The $\kappa -(BEDT-TTF{)}_{2}X$ materials present many similarities with cuprates, such as the presence of unconventional metallic properties and the close proximity of superconducting and antiferromagnetic phases. As in the cuprates, spin fluctuations are expected to play a crucial role in the onset of superconductivity. We perform a weak-coupling renormalization-group analysis to show that a superconducting instability occurs. Frustration in the antiferromagnetic couplings, which arises from the underlying geometrical arrangement of the lattice, breaks the perfect nesting of the square lattice at half-filling. The spin-wave instability is suppressed and a superconducting instability predominates. For the isotropic triangular lattice, there are again signs of long-range magnetic order, in agreement with studies at strong-coupling.

4 pages, 5 eps figs, to appear in Can. J. Phys. (proceedings of the Highly Frustrated Magnetism (HFM-2000) conference, Waterloo, Canada, June 2000)

References in corpus (3)

• Renormalization group analysis of the 2D Hubbard model
• Large-N solutions of the Heisenberg and Hubbard-Heisenberg models on the anisotropic triangular lattice: application to Cs${}_2$CuCl${}_4$ and to the layered organic superconductors $\kappa$-(BEDT-TTF)${}_2$X
• The Mott Metal-Insulator transition in the half-filled Hubbard model on the Triangular Lattice

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• Flow of the quasiparticle weight in the N-patch renormalization group scheme
• Quantitative functional renormalization-group description of the two-dimensional Hubbard model
• Resilience of d-wave superconductivity to nearest-neighbor repulsion
• Dynamical properties of a strongly correlated model for quarter-filled layered organic molecular crystals
• Antagonistic effects of nearest-neighbor repulsion on the superconducting pairing dynamics in the doped Mott insulator regime
• Dominant Superconducting Fluctuations in the One-Dimensional Extended Holstein-Extended Hubbard model
• Correlated Phases of Population Imbalanced Fermi-Fermi Mixtures on an Optical Lattice
• Ferromagnetism and triplet superconductivity in the two-dimensional Hubbard model
• $d$-wave Superconductivity in the Hubbard model on the isotropic triangular lattice and a possibility of the chiral $d+id$ pairing as a quasi-stable state
• d_{xy}-Density wave in fermion-fermion cold atom mixtures