RESUMO
Titanium diffusion from (001) SrTiO3 (STO) substrates into CoFe2O4 (CFO) films grown using pulsed laser deposition is reported. To elucidate the reasons for Ti interdiffusion, a comparative study of CFO films grown on MgAl2O4 (MAO) and STO substrates, buffered by thin STO and MAO layers, has been made. It is shown that whereas bottom STO layers always result in Ti migration, a thin MAO layer, only 8 nm thick, is effective in blocking it. We argue that this success relies on the lower mobility of Ti ions in the MAO lattice compared to that of CFO. This result should contribute to the development of high quality epitaxial heterostructures of dissimilar complex oxides.
RESUMO
Cobalt ferrite nanowires with a diameter of about 30 nm have been prepared inside anodized aluminum oxide (AAO) templates with one end closed nanopores using a vacuum infiltration method. The ferrite phase formation was confirmed by X-ray diffraction. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to characterize the morphology and structure of nanowires. SQUID magnetometer measurement showed that the nanowires to have both ferrimagnetic and superparamagnetic characteristics. A model for formation of discontinuous nanowires and particle agglomeration inside the template is discussed to explain these results.