Theoretical Studies Of Phase Transition Of A Magnetic Binary Mixture

Using the thermodynamics of binary mixtures, we calculate the free energy of a magnetic binary mixture. The phase transitions inφ=0.5 binary mixtures andφ<0.5 binary mixtures are analyzed and discussed using mean-field Bragg-Williams theory. It is found that.1. Without staggering effect, there exists a second-order phase transition in a binary mixed magnetic system. The relation between phase transition temperaturezT/(znJ₁) , the radio of the interaction of the different particles to that of the same particles J₂/J₁ , and the volume radioφ, is given by . (1) When J₂/J₁>1, the interaction of the different particles J₂ is dominant, and the volume radioφis located at the edge, namely, one of the components is relatively less than the other. The second order phase transition temperature T/(znJ₁) is relatively low. Whenφ=0.5, i.e. two of the components are magnetic mixed equally, the second order phase transition temperature reaches the maximum. (2) J₂/J₁=1 , the interaction of the different kinds of particles is equal to that of the same kinds of particles. The temperature is T = znJ₁. The borderline of the second order phase transition reduce to that the system only has one kind of component. (3) When J₂/J₁<1 , the interaction of the same particles J₁ is dominant, and the volume radioφis located at the edge, i.e. one of the components is relatively less than the other. The second order phase transition temperature T/(znJ₁) is relatively high. Whenφ=0.5, i.e. two of the components are magnetic mixed equally, the second order phase transition temperature reaches the minimum. 2. Considering staggered effect, m_s≠0, (1) when J₂/J₁ is relatively small on a binary mixed...