A combination of reactive force field molecular dynamics and hybrid-exchange density functional theory (DFT) generates a defective structure of $\mathrm{Rh}\text{−}{\mathrm{C}}_{60}$ possessing an inter-cage link. Hybrid-exchange DFT is used within periodic boundary conditions to investigate the long-range magnetic coupling between the resulting defects. Inelastic neutron scattering experiments highlight the presence of hydrogen chemically bonded to carbon in the magnetic samples. A simple spin model previously applied to studies of planar conjugated $\pi$ electron systems is used to illustrate the mechanism through which chemically bonded hydrogen leads to a ferromagnetic ground state for this system.

• Received 30 April 2004

DOI:https://doi.org/10.1103/PhysRevB.70.041403