Blume-Emery-Griffiths model for a magnetic bilayer. Magnetocaloric properties in the presence of the 1st-order phase transitions

In the paper the Blume-Emery-Griffiths model is studied for a magnetic bilayer with coordination number z = 5. The Cluster Variational Method in Pair Approximation is employed. A special emphasis is put on the magnetic and magnetocaloric properties in the cases of the 1st order phase transitions. For such cases the magnetization, quadrupolar moment and magnetic entropy, as well as the isothermal entropy change and the adiabatic temperature change during demagnetization process are calculated. It is shown that in the vicinity of the temperature corresponding to the 1st order phase transitions the adiabatic demagnetization is not possible. Instead, the demagnetization process with the smallest entropy production is proposed.

Automated summary

The paper investigates the Blume-Emery-Griffiths model for a magnetic bilayer with coordination number z = 5. The Cluster Variational Method in Pair Approximation is used, with a special emphasis on the magnetic and magnetocaloric properties in the cases of 1st order phase transitions.