Chemical Control of Magnetism: Oxidation-Induced Ferromagnetic Spin Coupling in the Chromium Dimer Evidenced by Photoelectron Spectroscopy

The photoelectron spectrum of the dichromium oxide cluster anion, [Formula presented], and the analysis by the density-functional theory revealed that the spins of the two Cr atoms in [Formula presented] are ferromagnetically coupled, and that its total spin magnetic moment is as large as [Formula presented]. This ferromagnetic spin coupling is induced by oxidation; the mixing of Cr [Formula presented] with O [Formula presented] orbitals plays an important role in a spin coupling between the localized electrons at the two Cr sites bridged by the O atom. The present finding is in marked contrast to the pure chromium dimer, which is known to be antiferromagnetic due to the strong sextuple Cr-Cr bond.