Intercalation of Bi2Sr2CaCu2O8+δ single crystal with C60: Characterization and micro-Raman investigation

Abstract

Micro-Raman and corroborative photoluminescence (PL); infrared (IR) absorption; scanning tunneling microscopy/spectroscopy (STM/STS) and x-ray diffraction (XRD) studies on the intercalation of Bi2Sr2CaCu2O8+δ (Bi-2212, host) with C60 (guest) reveal that intercalation drastically changes vibrational, electronic, and structural characteristics of both the guest and the host species. The predominant changes in vibrational modes such as splitting (651, 668 cm−1) in the radial mode (at 709 cm−1); anomalous intensity distribution; and appearance of forbidden modes in the Raman spectra of the guest have been related to the symmetry reduction in the guest sublattice and to the induced resonance effects due to the intercalation process. Further, the changes in Raman spectra corresponding to the host, such as the appearance of a strong Raman mode at 310 cm−1 (in the νCu–O region), redshift in the νBi–O mode, and the appearance of a band at 1443 cm−1 in the tangential mode region of the guest reveal the formation of semiconducting islands in the host sublattice due to the guest–host electron transfer process. Raman results have been correlated with PL, IR, STM/STS, and XRD data.