Magnetoconductivity in Bismuth Selenide–Magnetite Thermoelectric Nanocomposites, Positive to Negative Crossover and Linear Behavior

The effect of structural disorder on the electrical transport is systematically studied in Bi 2 Se 3 ‐Fe 3 O 4 nanograin‐bulk thermoelectric materials. Keeping the characteristics of the Bi 2 Se 3 matrix under control allows to evidence the role of localization and surface interaction in electronic transport in bulk nanostructured thermoelectric composites. Nanograin Bi 2 Se 3 ‐Fe 3 O 4 bulks present an enhanced thermoelectric performance compared to Bi 2 Se 3 and enable the realization of linear magnetoconductance at low temperatures in composite bulks. With the addition of Fe 3 O 4 , a crossover from positive to negative magnetoconductance is realized, more enhanced in c ‐axis textured samples. The observations are compatible with the presence of high mobility carriers at the Bi 2 Se 3 ‐Fe 3 O 4 interfaces of the material.