arXiv:cond-mat/0301067 · Physical Review B
Disorder-induced phases in higher-spin antiferromagnetic Heisenberg chains
Enrico Carlon, Péter Lajkó, Heiko Rieger, Ferenc Iglói
Abstract
Extensive density-matrix renormalization-group calculations for spin $S=1/2$ and $S=3/2$ disordered antiferromagnetic Heisenberg chains show a rather distinct behavior in the two cases. While at sufficiently strong disorder both systems are in a random singlet phase, we show that weak disorder is an irrelevant perturbation for the $S=3/2$ chain, contrary to what expected from a naive application of the Harris criterion. The observed irrelevance is attributed to the presence of a new correlation length due to enhanced end-to-end correlations. This phenomenon is expected to occur for all half-integer $S>1/2$ chains. A possible phase diagram of the chain for generic S is also discussed.