Magnetic entropy change in RCoAl (R = Gd, Tb, Dy, and Ho) compounds: Candidate materials for providing magnetic refrigeration in the temperature range 10 K to 100 K

Large magnetic entropy changes were observed in RCoAl compounds, where R = Gd, Tb, Dy, and Ho, at their Curie temperatures. These RCoAl alloys have a hexagonal, MgZn₂ structure and their Curie temperatures fall in the temperature range 10-100 K. A 'table-like' behaviour was found in the temperature dependence of the magnetic entropy change (- Δ S(T)) obtained in the soft magnetic GdCoAl alloys, which can be used either to fill up the gap (near 100 K) in the profile of magnetic entropy change versus temperature required by an eight-stage magnetic refrigerator or to complete an Ericsson circle. It has also been shown that soft ferromagnetic materials with Curie temperatures in the temperature range from 10 K to 100 K can be obtained by using multi-R elements instead of a single-R element in the RCoAl compounds.