Thus, below Tc the system is in the ferromagnetic phase, with one of two possible directions of the average spontaneous magnetization, so that the critical (Curie 39 ) temperature, given by Equat...Thus, below Tc the system is in the ferromagnetic phase, with one of two possible directions of the average spontaneous magnetization, so that the critical (Curie 39 ) temperature, given by Equation (???), marks the transition between the paramagnetic and ferromagnetic phases. (Since the stable minimum value of the free energy F is a continuous function of temperature at T=Tc, this phase transition is continuous.)
The minimum of the free energy occurs close to the h=0 solution m=m\ns0(θ)≡√3(1−θ), and writing m=m\ns0+δm we find δm to linear order in h as ...The minimum of the free energy occurs close to the h=0 solution m=m\ns0(θ)≡√3(1−θ), and writing m=m\ns0+δm we find δm to linear order in h as δm(θ,h)=h/2(1−θ).
