Self-assembled patterned CoFe2O4-SrRuO3 electrodes: Enhanced functional properties by polar nano-regions reorientation

Epitaxial CoFe2O4 (CFO) and SrRuO3 (SRO) nanopillar heterostructures were deposited on Pb(Mg1/3Nb2/3)(0.70)Ti0.30O3 (PMN-30PT) single crystal substrates by switch pulsed laser deposition (SPLD). Since the CFO nanopillars are insulating, and the SRO matrix conductive, this self-assembled nanopillar heterostructure served as a patterned electrode on PMN-PT, which then enhances the dielectric and piezoelectric constant of the substrate. Cross-sectional electron microscopy images revealed the formation of a nanopillar heterostructure layer with CFO nanopillars within a SRO matrix. AFM and XRD revealed good topography and epitaxy, indicating a high quality SRO-CFO self-assembled nanopillar structure. Using a SRO-CFO thin film patterned electrode, PMN-PT was found to have a notably higher (similar to 30%) dielectric constant with increasing electric field and enhanced transverse broadening in reciprocal spacing mapping (RSM) scans.