Large reversible magnetocaloric effect in the ferromagnetic pyrochlores R2Mn2O7 (R = Dy, Ho, Yb)

We report the large reversible magnetocaloric effect (MCE) in the cubic pyrochlores R2Mn2O7 (R = Dy, Ho, Yb) near their second-order ferromagnetic (FM) transition at T-c approximate to 39 K due to a simultaneous FM ordering of rear-earth R3+ and transition-metal Mn4+ localized moments. Under the magnetic field change of 1T (7T), the maximum magnetic entropy change -Delta S-M(max) is 5.7 (20.1), 4.3 (18.4), 3.9 (13.9) J.kg(-1) K-1, and the estimated magnetic refrigerant capacity RC reaches 20.0 (564), 18.4 (503.7), 13.1 (371.4) J.kg(-1) for Dy2Mn2O7, Ho2Mn2O7, and Yb2Mn2O7, respectively. We have discussed their magnetic properties and its correlation with MCE in terms of the intrinsic single-ion anisotropy of R(3+ )ions. Our results demonstrate that R2Mn2O7 cubic pyrochlores constitute a promising material platform for magnetic refrigeration applications in the intermediate temperature range.