Probing variable range hopping lengths by magneto conductance in carbonized polymer nanofibers*

Using magneto transport, we report hopping length scales in the variable range hopping conduction of carbonized polyacetylene and polyaniline nanoribers. In contrast to pristine polyacetylene nanofibers that show zero magneto conductance at large electric fields (it clarifies the charge and spin states of 1-D topological insulator, namely the solitons in polyacetylene nanofibers.), carbonized polymer nanofibers display a negative magneto conductance that decreases in magnitude but remains finite with respet to the electric field. We show that this behavior of magneto conductance is an indicator of the electric field and temperature dependence of hopping length in the gradual transition from the thermally activated to the activation-less electric field driven variable range hopping transport. This reveals magneto transport as a useful tool to probe hopping lengths in the non-linear hopping regime.
Reference: Kyung Ho Kim et. al., Scientific Reports 8, 4948 (2018)