| Giant Magnetoresistance (GMR) was observed in Cobalt-PTFE heterogeneous granular films. The samples were deposited on glass substrates by using the Pulsed Laser Deposition (PLD) technique. IR absorption spectra of the deposited PTFE showed similar characteristics with the bulk PTFE. The samples prepared exhibit a percentage change in resistance (MR%) of about 5% at room temperature with an applied magnetic field (H) of 10kOe. A significant change of the MR profile was observed when the magnetic field was applied in-plane and out-of-plane to the film. The temperature dependence of resistance of the samples shows that charge transportation is mainly due to tunneling between the metal particles in the sample. The magnetization curve reveals the superparamagnetic nature of the sample. The GMR effect can thus be interpreted by the spin-dependent electrons tunneling through the ferromagnetic metal granules (cobalt) in the insulating matrix (PTFE). An enhancement of MR% was observed at low temperature. |
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