Three-dimensional Ising-like system in an external field. Microscopic approach to description of the critical behaviour using the asymmetric [formula omitted] model

Abstract

The new microscopic approach to derive complete explicit expressions for the thermodynamic characteristics (including the scaling functions) of a three-dimensional Ising-like system is briefly described in the vicinity of the critical point for regions of the so-called weak and strong external fields. The description of the critical behaviour of the system in an external magnetic field is based on the first principles of statistical physics and is naturally realized by using the non-Gaussian spin-density fluctuations, namely, the quartic measure density with the even and odd powers of the variable (the asymmetric ρ 4 model). The thermodynamic characteristics of the system are given as functions of the temperature and field in the cases of both weak and strong fields for temperatures above and below T c ( T c is the phase-transition temperature in the absence of an external field).