2005/04/30 by G. Roux, S. R. White, S. Capponi +2
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.72.014523
published as Phys. Rev. B 72, 014523 (2005) · 5 pages, 7 figures, to appear in PRB
arxiv created 2005/05/27 · arxiv updated 2009/12/01
The effect of a ring exchange on doped two-leg ladders is investigated combining exact diagonalization (ED) and density matrix renormalization group (DMRG) computations. We focus on the nature and weights of the low energy magnetic excitations and on superconducting pairing. The stability with respect to this cyclic term of a remarkable resonant mode originating from a hole pair-magnon bound state is examined. We also find that, near the zero-doping critical point separating rung-singlet and dimerized phases, doping reopens a spin gap.