Frustrated Hubbard ladders and superconductivity in kappa-BEDT-TTF organiccompounds

Half-filled two-leg Hubbard ladders have spin-gapped short-range antiferrom agnetic correlations while three-leg ladders have power law antiferromagnet ic correlations, and both systems have d(x)(-y)(2)(2)-power-law pairing cor relations when they are doped. These ladders exhibit some of the phenomenol ogy seen in the layered cuprates. Here we report results for half-filled fr ustrated Hubbard ladders, based upon two-leg ladder segments taken from a t ight-binding model of kappa-BEDT-TTF. Although these ladders are half-fille d, varying the degree of frustration can drive them across an insulator-met al transition. Here we study the spin, charge and pairing correlations of t hese frustrated ladders near the insulator-metal transition. We find that t hey exhibit some of the phenomenology seen in the organic BEDT materials an d suggest that materials containing weakly coupled ladders of this type wou ld be interesting to synthesize.