Magnetoresistivity of cobalt-polytetrafluoroethylene granular composites

Abstract

Giant magnetoresistance (GMR) was observed in a heterogeneous granular film with polymer matrix. Cobalt and polytetrafluoroethylene (PTFE) were deposited on glass substrates by using the pulsed laser deposition technique. IR absorption spectra of the deposited PTFE showed similar characteristics with the bulk PTFE. The granular samples exhibit a resistance change of about 5% (at 10 kOe) at room temperature. The temperature dependence of resistance of the samples shows that charge transportation is mainly due to tunneling between the metal particles. The GMR can thus be interpreted by the spin-dependent electrons tunneling through the ferromagnetic metal granules (cobalt) in the insulating matrix (PTFE).