Study Of The Critical Behaviors And Magnetic Properties In The Random Three-dimensional Ferromagnetic System

This article mainly discusses the phase transition properties of single spin (s=1) ferromagnetic system. We know that the ferromagnet with strong magnetism in the condition of low temperature will turn into paramagnet when the temperature reachs the Curie temperature. In this article we study the bond-diluted Blume-Capel (BCM) with the random crystal field in an applied field and the random bond (BCM) with the random crystal field, The phase diagrams display the Curie temperature dependences of the applied field, the crystal field, the bond concentration and the random crystal field concentration for simple cubic lattice. In the bond-diluted BCM with the random crystal field in an applied field, the Curie temperature decreases monotonously with the increasing of the crystal field. The system with a larger crystal field can exhibit tricritical point at which the phase transition changes from second to first order. The tricritical point is depressed with decreasing the random concentration of the crystal field, at the same time the reentrant phenomenon occurs. The system will be ordered entirely when the random concentration is small enough at low temperature. The bond dilution can depress the order phase effectively; The Curie temperature increase when the applied field is introduced, at the same time, magnetization curve appears double- peak distribution due to a larger crystal field. Under the random bond condition, in particular, when there exists antiferromagnetic interaction, we obtain many meaningful results.