Magnetic and magnetocaloric properties of Gd6−xRxMn23 (R = Y, Sm, Tb, Dy, Ho and Er) compounds

The magnetic properties and magnetocaloric effect of Th6Mn23-type Gd3R3Mn23 (R = Y, Sm, Tb-Er) compounds and Gd6−xYxMn23 and Gd6−xErxMn23 (x = 1, 2, 3) solid solutions are studied by DC magnetization measurements. The Gd3R3Mn23 compounds have magnetic and magnetocaloric properties which are intermediate between those of Gd6Mn23 and those of the corresponding R6Mn23 compound. The study of the Gd6−xYxMn23 and Gd6−xErxMn23 solid solutions shows that both magnetic and magnetocaloric properties evolve continuously upon Gd substitution. These results are in agreement with the existence of a single crystallographic site (24e) for the lanthanide atoms in the cubic Th6Mn23-type structure. The experimental results also confirm that the high Curie temperature typical for R6Mn23 compounds is mainly dominated by the Mn-Mn magnetic interactions, with non-negligible R-Mn magnetic interactions. The −ΔSM maxima of moderate magnitude observed at low temperature are associated with the magnetic ordering of the lanthanide sublattices and can be altered by Gd substitution. The potential interest of these phases for cooling applications is briefly discussed.