Nanocomposites and nanomaterials

Optical properties of nanocomposites based on the transitional metal oxides
Barlas T.1, Kondratenko O.1, Mamykin S.1, Romanyuk V.1, Savkina R.1, Smirnov A.1, Naseka Iu.1, Strelchuk V.1, Mulenko S.2, Demchenko I.3, Walczak M.4
1 V.Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, 41 Naukyav, Kyiv 03028, Ukraine 
E-mail: barlas@isp.kiev.ua 
2 G. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine, 36 Vernadsky Blvd, Kyiv 03142, Ukraine 
3 Institute of Physics, Polish Academy of Science, al. Lotników 32/46, PL-02-668 Warsaw, Poland 
4 Corrosion &Protection Centre School of Materials The University of Manchester, Sackville Street, The Mill Manchester, M1 3BB, United Kingdom 

An integration of silicon and oxide-based composite nanostructures characterized by a close coupling of magnetization and polarization properties (in our case transitional metal oxides Fe2O3-X(0≤x≤1) and Cr3-xO3-y(0≤x≤2; 0≤y≤2)) can allow to obtain new multifunctional structure, e.g. for magnetoresistive memory or for magnetic diodes on non-magnetic substrate (<100> Si). Nanometric iron and chromium oxide layers, their multilayer combinations and solid solutions were grown on silicon and glass substrates by the reactive pulsed laser deposition techniques at various technological parameters such as oxygen pressure in the reactor, substrate temperature, number of laser pulses. Systematic studies of the optical properties of these structures using spectral ellipsometry in the NIR–VIS–UV range, light transmition-reflection measurements in the VIS range, X-ray photoelectron and Raman spectroscopy allow to describe investigated structures in the framework of the optical model of the multilayer structure with composite layers. Absorption coefficient and refractive index, layer thickness d of composite layers were obtained. It is shown that oxides are present on the surface in different phases, and the technological parameters and composition of these films significantly affect their optical properties in NIR–VIS–UV range.