Random transverse single-ion anisotropy in the spin-1 Blume-Capel quantum model

We have studied the effects of the random transverse single-ion anisotropy in the phase diagram and in the thermodynamic properties of the spin-1 Blume-Capel quantum model, which has been used the approach the mean-field theory based on the Bogoliubov inequality for the Gibbs free energy. The phase diagrams were obtained in the temperature tau = k(B)T/zJ versus single-ion anisotropy delta(x) = D-x/zJ plane for several values of delta(y) = D-y/zJ, p and q. The results show that there is a tricritical behavior only in the range of delta(y) given by -0.048 <= delta(y) < 0.5. This behavior is shown again by the curves of the magnetization m as a function of temperature tau with corresponding values of delta(y), p and q. (C) 2019 Elsevier B.V. All rights reserved.