Substrate Control of Anisotropic Resistivity in Heteroepitaxial Nanostructured Arrays of Cryptomelane Manganese Oxide on Strontium Titanate
Anais E. Espinal, Yonggao Y. Yan, Lichun Zhang, Laura Espinal, Aimee Morey, Barrett O. Wells, Mark Aindow, Steven L. Suib
Resistivity and resistance measurements have been carried out for thin films of cryptomelane-type manganese oxide (OMS-2) grown onto (001), (110) and (111)STO single crystals substrates via pulsed laser deposition. Combined with controlled synthesis and structure characterization, the influence of the orientation of the nanofibers on the electrical conduction has been identified. The symmetries of the (001) and (111)STO substrate surfaces gave deposits consisting of multiple nanofiber arrays with isotropic in-plane resistivities . In contrast, only a single nanofiber array was formed on (110) STO giving highly anisotropic electrical properties with very low resistivity values measured parallel to the fibers. The results herein show that the OMS-2 deposit structure can be controlled via heteroepitaxial growth on STO; this effect could be exploited in areas such as sensing, selective catalysis, and nano-composites.