LARGE MAGNETORESISTANCE IN INTERCALATED CU OXIDES

Magnetism and electrical resistance as a function of magnetic field, t emperature, and chemical composition are studied in Cu oxides intercal ated with metal phthalocyanines MPc, where M is Fe or Ni, and Pc is C3 2H16N8. An unusually large positive magnetoresistance (MR) of similar to 1200% is observed in FePc-intercalated Bi2Sr2Can-1CunO2n+4 samples with two Cu-O layers in the unit cell (n=2). The magnitude of the MR d ecreased to 40% and similar to 0% in the FePc-intercalated n=3 and n=4 samples, respectively, and to similar to 300% in the NiPc-intercalate d n=2 sample.