Electronic structure of molecular superconductors containing paramagnetic 3d ions

Abstract

The results of x-ray fluorescence measurements of the molecular superconductors (ET)4[(H3O)Fe(C2O4) 3]·C6H5CN (Tc = 8.5 K) and (ET)4[(H3O)Cr(C2O4) 3]·C6H5CN (Tc ∼ 6 K) and molecular conductor (ET)4[(H3O)Fe(C2O4) 3]·C5H5N containing paramagnetic 3d ions are presented. The following transition of the x-ray emission valence spectra are monitored: C K α, N K α (2p→1s transition) and Fe L2,3, Cr L2.3 (3d4s→2p3/2,1/2 transition). It is found that the electronic structure of the solvents (benzonitrile, pyridine) that occupy the hexagonal cavities formed by the anionic layer is close to that of the neutral molecule. The ratio of the emission intensities of the peaks L2 to L3 for Fe and Cr is found to be 2.8-3.1 times higher for (ET)4[(H3O)Fe(C2O4) 3]·C6H5CN and (ET)4[(H3O)Cr(C2O4) 3]·C6H5CN than for pure metals. This indicates that the paramagnetic 3d ions are situated in highly insulating anionic layers. We did not find any changes in the C K α emission for different solvent molecules.