Intercalation of Bi- and Tl-oxide superconductors with conjugated ring-shaped organic molecules: X-ray, Raman scattering, microwave and magnetic studies

Abstract

The characterization of Bi- and Tl-oxides, intercalated with either benzene or metal-phthalocyanines MPc (M=Cu, Ni; Pc=C₃₂N₁₆H₈), by X-ray diffraction, Raman scattering and microwave absorption spectroscopies, as well as by DC and AC magnetization techniques, is reported. All the samples exhibit unusual magnetic behaviour at 300 K, similar to those reported earlier for the benzene-intercalated Bi-Oxides, observed in magnetization and microwave studies. The spectroscopic fingerprints of the phase responsible for the anomalies are identified. The broad vibrational modes at higher frequencies above 700 cm⁻¹ were observed in the intercalated samples and are at different frequencies from those of the pure organic species. We speculate that the magnetic anomalies are most likely not due to the host oxides, but rather to the appropriate spatial arrangement of the specific organic molecules, favoring the orbital magnetism of delocalized π-electrons over the molecules.