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F. Tuna

Publications and source records attributed to F. Tuna.

2 recordsLinked to original sources

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.

cond-mat.mtrl-sci

Limits on intrinsic magnetism in graphene

We have studied magnetization of graphene nanocrystals obtained by sonic exfoliation of graphite. No ferromagnetism is detected at any temperature down to 2 K. Neither do we find strong paramagnetism expected due to the massive amount of edge defects. Rather, graphene is strongly diamagnetic, similar to graphite. Our nanocrystals exhibit only a weak paramagnetic contribution noticeable below 50K. The measurements yield a single species of defects responsible for the paramagnetism, with approximately one magnetic moment per typical graphene crystallite.

cond-mat.mes-hall