Antiferromagnetism in a doped spin-Peierls model: classical and quantum behaviors

We address the problem of antiferromagnetism in a two dimensional model of doped spin-Peierls system, at the classical and quantum levels. A Bethe-Peierls solution is derived for the classical model, with an ordering temperature proportional to the doping concentration. The quantum model is treated in a cluster renormalization group showing a finite randomness behavior and an antiferromagnetic susceptibility at low temperature.