Soft x-ray magnetic circular dichroism in molecular based magnet

Abstract

The molecular based megnet Cs^(I) [Ni^(II)Cr^(III)(CN)6] * 2H2O is a ferromagnet with a Curie temperature Tc = 90 K. Its structure consists of face centered cubic lattice of Ni^(II) ions connected by Cr(CN)6 entities. We have recorded X-ray Magnetic Circular Dichroism (XMCD) at the L2,3 edges of Ni^(II). Through Crystal Field Multiplet calculation we have determined the total megnetic moment carried by the Ni^(II). By using sum rules derived for XMCD, it has been possible to extract orbital and spin contributions to the total magnetic moment. A somewhat too small magnetic moment is found on nickel. A complete calculation taking into account the multiplet coupling effect and the covalent hybridization allowed to determine the precise ground state of nickel and showed that hybridization with surrounding nitrogen atoms is not responsible for the experimental low nickel magnetic moment.