The Critical Behaviors And Magnetic Properties Of Bond And Crystal Field Dilution Blume-Emery-Griffiths Model

This paper discusses the critical behaviors and magnetic properties of the spin-1 bond and crystal field dilution Blume-Emery-Griffiths (BEG) model on simple cubic lattice within the framework of effective field theory (EFT). Some new phenomena are presented due to the interplay between bond and crystal field dilution, crystal field and the ratio of biquadratic and exchange interaction (α). When crystal field is negative and positive ratio α change in a certain range, there exist double tricritical points (TCPs) in phase transition lines in T - D plane. The first-order phase transition between double TCPs is enlarged with increasing of ratio α at a fixed crystal field dilution concentration, while this first-order phase transition will shrink when bond dilutionconcentration is fixed. In T - p plane, there exist two bond percolation thresholds fornegative crystal field and α > 0. In the presence of magnetic field, the common action of bond and crystal field dilution leads to the exhibition of an irregular initial magnetization curve. The peak of susceptibility curve has an explicit decline. In M-T plane, the magnetization curves show a discontinuity and take on a vertical leap in a restricted small range of magnetic field when negative crystal field is larger and the ratioα is positive (α>0). In x^-1 -T plane, the behaviors exhibited by susceptibilitycurve qualitatively similar to the corresponding experiment results. When α <-1, the phase diagrams present both staggered quadrupolar-paramagnetic and ferromagnetic-paramagnetic phase boundaries, separated by a bicritical point. We discuss the influence of two dilution factors, anisotropy parameter and the ratio α on phase boundaries and bicritical point. Some meaningful results are obtained.