Random Spin-1 Quantum Chains
  We study disordered spin-1 quantum chains with random exchange and biquadratic interactions using a real space renormalization group approach. We find that the dimerized phase of the pure biquadratic model is unstable and gives rise to a random singlet phase in the presence of weak disorder. In the Haldane region of the phase diagram we obtain a quite different behavior. 
Beatriz Boechat, Andreia Saguia (Universidade Federal Fluminense),   Mucio Continentino (Universidade Federal Fluminense and...