  We report on the low temperature tunnel magnetoresistance (MR) in quasi
one-dimensional (1D) nanofibers made of conjugated polymers. The MR voltage
bias dependence reveals an enhancement (at low biases) and the oscillatory
behavior at temperatures below 10 K. The low temperature isotropic MR behavior
has been attributed to the charging effects in the polymer nanofiber which
considered as an array of small conducting regions separated by nano barriers.
These effects at low temperatures lead to the single electron tunneling
represented by the Coulomb blockade regime as well as to an enhancement and
oscillation of the tunnel MR.
