Magnetic refrigerants for the 4.2-20 K region: garnets or perovskites?

Rare earth orthoaluminates (REOA) REAlO 3 , the compounds with perovskite structure, are compared with garnets with a view to finding an effective working material for 4.2-20 K magnetic refrigerators. It appears from the meanfield calculations that orthoaluminates are more advantageous than Gd 3 Ga 5 O 12 , Dy 3 Ga 5 O 12 and Dy 3 Al 5 O 12 , the garnets which so far have been considered the most promising refrigerants.