Magnetic and reversible magnetocaloric properties of (Gd1−xDyx)4Co3 ferrimagnets

Magnetic properties and magnetocaloric effect of the ferrimagnetic compounds Gd4Co3 and (Gd0.9Dy0.1)4Co3 have been studied. In Gd4Co3, two successive magnetic-entropy changes occur due to a spin-reorientation transition at TSR=163 K and a ferrimagnetic-magnetic ordering transition at TC=220 K. For a field change from 0 to 5 T, −ΔSMmax at TC is 5.74 J/kg K, the full width at half maximum (δTFWHM) of the −ΔSM versus T curve has a high value of 131 K, and the refrigerant capacity is as high as 575 J/kg. TC can easily be tuned by Dy substitution for Gd and the magnetic-entropy change is increased simultaneously. −ΔSMmax of (Gd0.9Dy0.1)4Co3 at TC=145 K for the same field change has increased to 8.47 J/kg K. Our studies suggest that the successive magnetic transitions could enlarge the temperature interval, which makes this type of material meaningful for magnetic refrigeration in wider temperature regions than conventional materials.