Mott variable-range hopping and weak antilocalization effect in heteroepitaxial Na2IrO3 thin films

Iridate thin films are a prerequisite for any application utilizing their cooperative effects resulting from the interplay of strong spin-orbit coupling and electronic correlations. Here, heteroepitaxial Na2IrO3 thin films with (001) out-of-plane crystalline orientation and well-defined in-plane epitaxial relationship are presented on various oxide substrates. Resistivity is dominated by a three-dimensional variable-range hopping mechanism in a large temperature range between 300 K and 40 K. Optical experiments show the onset of a small optical gap E-go approximate to 200 meV and a splitting of the Ir 5d-t(2g) manifold. Positive magnetoresistance below 3 T and 25 K shows signatures of a weak antilocalization effect.