Synthesis and magneto-transport properties of single PEDOT/Ni and PEDOT/Ni30Fe70 core/shell nanowires

Single polyethylenedioxythiophene (PEDOT) nanowires bridging pairs of electrodes were utilized as positive templates to create PEDOT/Ni and PEDOT/Ni30Fe70 core/shell nanowires by electrodepositing ferromagnetic material (i.e.. Ni and Ni30Fe70) on the entire assembly, including both the electrodes and nanowire. The temperature dependence of the electrical resistance indicated that electrons are transported predominately through the ferromagnetic shell. The magnetoresistive (MR) behavior of the core/shell nanowires was investigated as a function of temperature, magnetic field orientation, shell thickness, and composition. The MR behavior of the PEDOT/Ni core/shell nanowires was anomalous for low applied magnetic fields, deviating from expected anisotropic magnetoresistance, with positive Delta R/R-0 values for all field orientations. PEDOT/Ni30Fe70 core/shell nanowires displayed the opposite behavior, with negative Delta R/R-0 for both longitudinal and transverse field orientations. The origin of this magnetoresistive behavior is postulated to be a geometry induced domain wall effect. (C) 2011 Elsevier Ltd. All rights reserved.