ar X iv : c on d - m at / 9 71 02 76 v 1 2 8 O ct 1 99 7 Numerical analysis of the bond - random antiferromagnetic S = 1 Heisenberg chain
نویسنده
چکیده
Ground state of the bond-random antiferromagnetic S = 1 Heisenberg chain with the biquadratic interaction −β ∑ i(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 β ≈ 0 persists against the randomness; namely, no randomness-driven phase transition is observed until at a point of extremelybroad-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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