Very Large Magnetoresistance in Intercalated Cu-Oxides
Abstract
We report the observation of a very large magnetoresistance (MR) in polycrystalline materials, Cu-oxides intercalated by metal phthalocyanines, MPc (M=Fe, Ni, Pb; Pc=C_32H_16N_8). The samples were prepared by exposing high-temperature superconducting Cu-oxides (Bi-2212 and 2223 systems) to MPc vapor at 800 K. The X-ray powder diffraction, optical, FT IR/far IR, Raman, ESR, STM/STS data suggested that an intercalation of MPc molecules between the unit cell blocks occurred, expanding the c-axis by 0.3 to 0.45 nm (depending on the level of MPc uptake) and having a dramatic effect on both the superconducting and normal state properties of the host oxides. The samples of (FePc)_0.1Bi-2212 were ferromagnetic below 1100 K and exhibited a transition at 130 K manifested as a sharp decrease of the zero-field-cooled (but not the field-cooled) dc magnetization accompanied by an increase in dc resistance. These samples exhibited a very large positive MR of 1,250NiPc_0.1Bi2212, 25050
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.G2213G