Double exchange mediated ferromagnetic coupling between Co atoms in dicobalt complex

Abstract

Realization of the full technological potential of molecular magnets requires a fundamental understanding of the origin of magnetic coupling in molecular systems. Using gradient corrected density functional theory and Cl as a ligand we show that the magnetic coupling between Co sites in a di-cobalt complex can be manipulated. While the ferromagnetic states of Co2Cl6 and Co2Cl7 are 0.07 eV and 0.20 eV lower in energy than their respective antiferromagnetic states, they are nearly degenerate in Co2Cl8. The origin of ferromagnetic coupling is explained using the double exchange model caused by charge disproportionation.