A theory of higher-order correlations: Application to mixed spin systems

✍ Scribed by L. Šamaj

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 758 KB
• Volume: 161
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/0378-4371(89)90435-4

✦ Synopsis

A recently developed correlation reduction theory is generalized to mixed spin Ising models on the SC and BCC lattices. Since mixed spin systems have less translational symmetry than their single spin counterparts, some non-trivial technicalities are needed for the detailed application of the method. The evaluated transition temperatures for mixed spin-~-spin-S (S = I ~ , ~) in a :, 1,., .... models are remarkable agreement with those obtained by the extrapolation of high-temperature series expansions. The calculation of the phase diagram for mixed spins ~ and spins I with uniaxial anisotropy A suggests that the system cannot undergo a second-order phase transition for high values of the anisotropy A. This conclusion is in contradiction to the recent result of the mean-field renormalization group.