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We have prepared composites with anisotropic microstructure consisting of silver nanoparticles and zinc oxide pillars using an oblique angle deposition technique, and examined the optical response originating from their anisotropic morphology. The sample was obtained in three steps. First, the assembly of silver nanoparticles was prepared on a silica glass substrate by electron-beam deposition of the silver thin film and subsequent heat treatment. Next, zinc oxide was obliquely grown by using a pulsed laser deposition. Finally the zinc oxide was crystallized by the post annealing to make an array of inclined pillars grown on the top of the silver nanoparticles. The structure and morphology of the composites were elucidated by a combination of X-ray diffraction analysis and transmission electron microscopy. Optical rotation spectroscopy clarifies that the composite shows optical birefringence due to its inclined pillar morphology. The optical rotation spectrum exhibits two peaks, one being associated to the localized surface plasmon resonance of the silver nanoparticles and the other the excitons in the zinc oxide pillars. The present fabrication method is simple and can be applied to obtain anisotropic composites with relatively large dimensions.

Multiferroic materials have been the subject of intense study, but it remains a great challenge to synthesize those presenting both magnetic and ferroelectric polarizations at room temperature. In this work, we have successfully obtained LiNbO3-type ScFeO3, a metastable phase converted from the orthorhombic perovskite formed under 15 GPa at elevated temperatures. A combined structure analysis by synchrotron X-ray and neutron powder diffraction and high-angle annular dark-field scanning transmission electron microscopy imaging reveals that this compound adopts the polar R3c symmetry with a fully ordered arrangement of trivalent Sc and Fe ions, forming highly distorted ScO6 and FeO6 octahedra. The calculated spontaneous polarization along the hexagonal c-axis is as large as 100 μC/cm(2). The magnetic studies show that LiNbO3-type ScFeO3 is a weak ferromagnet with TN = 545 K due to a canted G-type antiferromagnetic ordering of Fe(3+) spins, representing the first example of LiNbO3-type oxides with magnetic ordering far above room temperature. A comparison of the present compound and rare-earth orthorhombic perovskites RFeO3 (R = La-Lu and Y), all of which possess the corner-shared FeO6 octahedral network, allows us to find a correlation between TN and the Fe-O-Fe bond angle, indicating that the A-site cation-size-dependent octahedral tilting dominates the magnetic transition through the Fe-O-Fe superexchange interaction. This work provides a general and versatile strategy to create materials in which ferroelectricity and ferromagnetism coexist at high temperatures.