Phase diagrams of spin-1 Blume-Capel model with bimodal random crystal and trimodal random magnetic fields

The phase diagrams of spin-1 Blume-Capel (BC) model under the constraints of bimodal random crystal and trimodal random magnetic fields are investigated by employing the lowest approximation of the cluster variation method (LACVM). The crystal field is either turned on with probability 1 - q or turned off with q , while the magnetic field is either turned off with probability p or turned on up or down for the chosen axis with ( 1 - p ) / 2 randomly. The phase diagrams are calculated by exploiting the thermal variations of the order-parameters on the ( D / J , k B T / J ) , ( p , k B T / J ) , ( q , k B T / J ) and ( h / J , k B T / J ) planes. It is found that the model presents first- and second-order transitions, a few types of the critical temperatures including the tricritical points. It also exhibits reentrant behavior, i.e. double second-order phase transitions.