Engineering Physics Annotation << Back PHASE TRANSITIONS IN SPIN SYSTEMS WITH A FROZEN DISORDER A.K.MURTAZAEV, A.B. BABAEV, Ya.K. ABUEV, G.Ya. ATAEVA The results obtained on the basis of the investigation of phase transitions and the critical behavior of three-dimensional structures described by disordered Potts models with the number of spin states q=3 and q=4 are discussed. It is shown that in the three-dimensional Potts model with the number of spin states q=3, the introduction of a small concentration of nonmagnetic impurities leads to a second-order phase transition. While in the Potts model with q=4, a change in the first-order phase transition to a second-order phase transition is observed in a strongly diluted regime (p=0,65). Using the histogram Monte Carlo method for these models, the values of tricritical points in the phase diagram are determined. Key words: Potts model, frozen disorder, phase transitions, tricritical point. Contacts: E-mail: b_albert78@mail.ru Pp. 026-030.