Crystal structure and anisotropy of iodine-intercalated Bi2Sr2Ca n?1Cu n O x

Abstract

The electronic state and structural configuration of the intercalated iodine species in stage-1, I-Bi2Sr2Ca n−1Cu n O x (n = l, 2), have been studied through polarization-resolved Raman and129I Mossbauer spectroscopy. The polarization dependence of the Raman spectra and the Mossbauer measurement confirmed the dominant species to be triiodide ions, I 3 − , with alignment of these linear molecules either along thea- orb-axis in the host crystals. Transport measurements such as thermoelectric power and Hall coefficient clearly indicated that hole carriers are doped into the CuO2 planes upon intercalation, by whichT c of the host superconductor is changed. Furthermore, based on resistivity measurements in a magnetic field, we suggest that the iodine intercalation leads to a decrease of the anisotropy both in normal and superconducting states, suppressing the extremely two-dimensional character of the Bi2Sr2Ca n−1Cu n O x systems.