MAGNETOCALORIC EFFECT IN STRONG MAGNETIC-FIELDS

Calculations of magnetic entropy change, ΔSM, and magnetocaloric effect, ΔT, in 3d and 4f magnetics have been carried out, based on the molecular field theory. ΔSM and ΔT have been studied as a function of Debye temperature, θD, Lande factor, gj, quantum number of total mechanical momentum, J, and also of magnetic phase transition temperatures. Limiting values of ΔSM and ΔT have been determined in extremely strong magnetic fields. The results obtained are compared with experimental data. It is shown that the use of ferromagnetic alloys Tbx Gd1-x as operating devices of magnetic refrigerating machines in the room temperature range is more efficient than the use of pure Gd. These alloys have been found to have high specific refrigerant capacity over a wide range of fields from 0.1 to 6 T, which enables one to develop highly economic refrigeration devices in which weak fields are applied. © 1990.