New critical behaviour of the three-dimensional Ising model with nearest-neighbor, next-nearest-neighbor and plaquette interactions

摘要

The critical and multicritical behavior of the simple cubic Ising model withnearest-neighbor, next-nearest-neighbor and plaquette interactions is studiedusing the cube and star-cube approximations of the cluster variation method andthe recently proposed cluster variation--Pad\'e approximant method. Particularattention is paid to the line of critical end points of theferromagnetic-paramagnetic phase transition: its (multi)critical exponents arecalculated, and their values suggest that the transition belongs to a noveluniversality class. A rough estimate of the crossover exponent is also given.