Modification of the electrical properties in Fe-Al2O3 granular thin films due to increased bias potential

We studied the electrical properties in Fe-Al2O3 granular films when the injected direct current or bias potential are varied in the low-field regime (eΔV⪡kBT). Measurements of the electrical resistance as a function of temperature and applied bias at different temperatures were performed. We found that the electrical properties are best described using variable range hopping. The variation in resistance showed unexpected characteristics in distinct regions of potential. These regions of potential could be due to modification of the electronic localization length. We have shown that the electrical resistance decreases when the applied bias and/or current increases. We associate this behavior of the resistance with the activation of new electronic paths. The total resistance of our samples is reduced as additional parallel electronic paths are formed.