Cryogenic magnetocaloric effect in the Fe-17 molecular nanomagnet.

We study the magnetothermal properties of magnetically isotropic high-spin molecular nanomagnets containing 17 Fe3+ ions per molecule linked via oxide and hydroxide ions, packed in a crystallographic cubic symmetry. Low-temperature magnetization and heat capacity experiments reveal that each molecular unit carries a net spin ground state as large as S = 35/2 and a magnetic anisotropy as small as D = -0.023 K, while no magnetic order, purely driven by dipolar interactions, is to be expected down to very-low temperatures. These characteristics suggest that the Fe-17 molecular nanomagnet can potentially be employed as a sub-Kelvin magnetic refrigerant. (C) 2012 Elsevier Ltd. All rights reserved.