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Numerical Analysis of the Bond-Random Antiferromagnetic S=1 Heisenberg Chain

Yoshihiro Nishiyama

cond-matarXiv:cond-mat/9710276

Abstract

Ground state of the bond-random antiferromagnetic S=1 Heisenberg chain with the biquadratic interaction -βΣi(Si Si+1)2 is investigated by means of the exact-diagonalization method and the finite-size-scaling analysis. It is shown that the Haldane phase β0 persists against the randomness; namely, no randomness-driven phase transition is observed until at a point of extremely-broad-bond distribution. We found that in the Haldane phase, the magnetic correlation length is kept hardly changed. These results are contrastive to those of an analytic theory which predicts a second-order phase transition between the Haldane and the random-singlet phases at a certain critical randomness.

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