Gd@C82: Origin of the Antiferromagnetic Coupling between Endohedral Gd and the Free Spin on the Carbon Cage

Abstract

The structure and magnetic ground state of the endohedral metallofullerene Gd@C82 is confirmed by relativistic density functional calculations. The experimentally observed reduction of the magnetic moment of Gd@C82 with respect to that of a free Gd3+ ion is explained by a small hybridization between unoccupied Gd-4f states and carbon-π states, resulting in a presumably generic antiferromagnetic coupling of the Gd-4f spin with the remaining unpaired spin in the hybridized molecular orbital.