Fabrication of Nb nanopin electrodes and their influence on multiferroic properties of BiFeO3 thin films

Abstract

We report enhanced multiferroic properties of BiFeO3 (BFO) thin films by depositing them on Nb nanopin bottom electrodes via spin-coating. The well-aligned Nb nanopin array was prepared from wet etching of an anodic aluminum oxide (AAO) nanotemplate. X-ray diffraction (XRD) measurement revealed that the BFO thin films were polycrystalline. The BFO thin films fabricated on Nb nanopin electrodes exhibited improved ferroelectricity with a remnant polarization (Pr) of 37.5 μC/cm2 and a coercive electric field (Ec) of 98 kV/cm, which was better than those (Pr ~ 32.9 μC/cm2 and Ec ~ 217 kV/cm) on the Nb film electrodes. We investigated leakage current, polarization switching speed as well as ferromagnetism, which also exhibited the improvement of BFO thin films on Nb nanopin electrodes. Significantly, we suggest that an enhanced electric field and surface-volume ratio of the Nb nanopin electrodes contribute to enhancement of the multiferroic properties of the BFO thin films.