Strain-driven nanodumbbell structure and enhanced physical properties in hybrid vertically aligned nanocomposite thin films

Abstract

Constructing vertical or lateral heterointerfaces using nanocomposite structures is an effective approach for tuning the overall strain state and the resulting physical properties of functional complex oxides. A hybrid La0.7Sr0.3MnO3 (LSMO)—CeO2 nanocomposite thin film with a novel nanodumbbell structure has been heteroepitaxially constructed by sequentially building composite bilayers with different two-phase volumetric ratios. Despite the different lateral diameters of the CeO2 domains in the two sequential nanocomposite layers, the CeO2 phase is coaxially grown within the LSMO matrix and vertically aligned to the substrate, producing the nanodumbbell structure. This structure is ascribed to a strain-driven nucleation and growth process. The high-density, tilted LSMO–CeO2 heterointerfaces exhibit distinct domain mismatch patterns—different from the vertical counterparts and thus present highly efficient strain tuning and highly improved magnetic and transport performances. More importantly, the well stacked CeO2 nanodumbbell structure suggests a strain-driven nucleation and growth mechanism in vertically aligned nanocomposite growth and demonstrates a new approach to enhance interfacial coupling and strain tunability in heteroepitaxial nanocomposite thin films by wise practice of the nucleation and growth mechanism.