Heterostructures of strongly correlated oxides demonstrate various intriguingand potentially useful interfacial phenomena. LaMnO 3 /SrMnO 3 superlattices are presented showcasing a new high-temperature ferromagnetic phase with Curie temperature, T C ≈360 K, caused by electron transfer from the surface of the LaMnO 3 donor layer into the neighboring SrMnO 3 acceptor layer. As a result, the SrMnO 3 (top)/LaMnO 3 (bottom) interface shows an enhancement of the magnetization as depth-profiled by polarized neutron reflectometry. The length scale of charge transfer, λ TF ≈2 unit cells, is obtained from in situ growth monitoring by optical ellipsometry, supported by optical simulations, and further confirmed by high resolution electron microscopy and spectroscopy. A model of the inhomogeneous distribution of electron density in LaMnO 3 /SrMnO 3 layers along the growth direction is concluded to account for a complex interplay between ferromagnetic and antiferromagnetic layers in superlattices.

Spatially resolved analysis of magnetic properties on the nanoscale remains challenging, yet strain and defects on this length-scale can profoundly affect a material's bulk performance. We present a detailed investigation of the magnetic properties of La0.67Sr0.33MnO3 thin films in both free-standing and nanowire form and assess the role of strain and local defects in modifying the films' magnetic properties. Lorentz transmission electron microscopy is used to measure the magnetocrystalline anisotropy and to map the Curie temperature and saturation magnetization with nanometric spatial resolution. Atomic-scale defects are identified as pinning sites for magnetic domain wall propagation. Measurement of domain wall widths and crystalline strain are used to identify a strong magnetoelastic contribution to the magnetic anisotropy. Together, these results provide unique insight into the relationship between the nanostructure and magnetic functionality of a ferromagnetic complex oxide film.

Chemical vapor deposition of iron pentacarbonyl (Fe(CO) 5 ) in an external magnetic field (B ¼ 1.00 T) was found to significantly affect the microstructure and anisotropy of as-deposited iron crystallites that could be transformed into anisotropic hematite (a-Fe 2 O 3 ) nanorods by aerobic oxidation. The deterministic influence of external magnetic fields on CVD deposits was found to be substrateindependent as demonstrated by the growth of anisotropic a-Fe columns on FTO (F:SnO 2 ) and Si (100), whereas the films deposited in the absence of the magnetic field were constituted by isotropic grains.TEM images revealed gradual increase in average crystallite size in correlation to the increasing field strength and orientation, which indicates the potential of magnetic field-assisted chemical vapor deposition (mfCVD) in controlling the texture of the CVD grown thin films. Given the facet-dependent activity of hematite in forming surface-oxygenated intermediates, exposure of crystalline facets and planes with high atomic density and electron mobilities is crucial for oxygen evolution reactions. The field-induced anisotropy in iron nanocolumns acting as templates for growing textured hematite pillars resulted in two-fold higher photoelectrochemical efficiency for hematite films grown under external magnetic fields (J ¼ 0.050 mA cm À2 ), when compared to films grown in zero field (J ¼ 0.027 mA cm À2 ). The dark current measurements indicated faster surface kinetics as the origin of the increased catalytic activity.

Flash sintering, a special case of electric field-assisted sintering, results in accelerated densification at lower temperatures than conventional sintering methods. However, the mechanisms remain elusive despite the wide application potential. In-situ electron microscopy studies reveal shrinkage of ZnO green bodies due to both heating and heating/biasing but show no obvious effect of the current on the behavior. In contrast, thin epitaxial ZnO films deposited on an Al2O3 substrate undergo a clear flash event during in-situ voltage application in the TEM, providing the first observation of flash sintering of a thin film. The specimen was captured in the high conductivity state where grain boundary motion was observed. The microscopic origins of the high conductivity state could not be detected, but may have the same underlying physical origin as the high conductivity memristive state.