Magnetic cryocooling with Gd3+ centers in a light and compact framework
  The magnetocaloric effect of gadolinium formate, Gd(OOCH)3, is experimentally determined down to sub-Kelvin temperatures by direct and indirect methods. This 3D metal-organic framework material is characterized by a relatively compact crystal lattice of weakly interacting Gd3+ spin centers interconnected via light formate ligands, overall providing a remarkably large magnetic:non-magnetic elemental weight ratio. The resulting volumetric magnetic entropy change is decidedly superior in Gd(OOCH)3 than in the best known magnetic refrigerant materials for liquid-helium temperatures and low-moderate applied fields. 
G. Lorusso, J. W. Sharples, E. Palacios, O. Roubeau, E. K. Brechin, R.   Sessoli, A. Rossin, F. Tuna, E. J. L. McInnes, D. C...
cond-mat.mtrl-sci