Study of the critical behaviour of three-dimensional Ising-like systems on the basis of theρ6model with allowance for microscopic parameters: II. Low-temperatureregion

Abstract

A microscopic approach to the investigation of the three-dimensionalIsing-like system thermodynamics below the phase transition temperatureTc isschematically presented within the framework of the higher non-Gaussian approximation(ρ6model) taking into account the corrections to scaling. A microscopic analogue ofthe Landau free energy is calculated. Explicit expressions for the thermodynamiccharacteristics are obtained as functions of the temperature and microscopicparameters of the system. The thermodynamic characteristics nearTcand their amplitudes are given for various values of the effective radius ofthe exponentially decreasing interaction potential (including the valuescorresponding to the nearest-neighbour interaction, the interaction betweenthe nearest and next-nearest neighbours, and that between the nearest,next-nearest, and third neighbours). The evolutions of the free energyof the system at the phase transition point, average spin moment, andspecific heat with increasing ratio of the potential effective radius to thesimple cubic lattice constant are plotted. The results of calculationsand their comparison with other authors’ data show that the ρ6model provides a better quantitative description of the criticalbehaviour of a three-dimensional Ising magnetic than the ρ4model.