FERROMAGNETIC PHASE-TRANSITION IN RANDOM POTTS SPIN CHAINS

We study the ferromagnetic phase transition in a model consisting of o ne-dimensional three-state Potts spin chains with random intrachain co uplings and comparatively weak ferromagnetic interchain couplings. Mea n-field theory is employed to decouple approximately the interchain co uplings. The transfer-matrix method is then used to study the resultin g effectively one-dimensional random-bond Potts model. The free energy as a function of the ferromagnetic order is calculated numerically an d a first-order ferromagnetic-paramagnetic phase transition is found o ver a wide range of degree of randomness.