Molecular nanoclusters as magnetic refrigerants: The case of Fe14 with very large spin ground-state

We report on the magnetic and thermal properties of the Fe₁₄ molecular nanocluster. We find a huge magnetocaloric response in the temperature range below 10 K. This is to large extent caused by its very large spin ground-state combined with an excess of entropy arising from the admixture of low-lying excited S states. We also show that the high degree of symmetry of the Fe₁₄ cluster core, resulting in a very small cluster magnetic anisotropy, enables the occurrence of long-range antiferromagnetic order below T_N = 1.87 K.