The atomic layer deposition (ALD) method was applied to grow thin polycrystalline BiFeO3 (BFO) films on Pt/SiO2/Si substrates. The 50 nm thick films were found to exhibit high resistivity, good morphological integrity, and homogeneity achieved by the applied ALD technique. Magnetic characterization revealed saturated magnetization of 25 emu/cm(3) with temperature-dependent coercivity varying from 5 to 530 Oe within the temperature range from 300 to 2 K. Magnetism observed in the films was found to change gradually from ferromagnetic spin ordering to pinned magnetic domain interactions mixed with weak spin-glass-like behavior of magnetically frustrated antiferromagnetic/ferromagnetic (AFM-FM) spin ordering depending on the temperature and magnitude of the applied magnetic field. Antiferromagnetic order of spin cycloids was broken in polycrystalline films by crystal sizes smaller than the cycloid length (∼60 nm). Uncompensated spincycloids and magnetic domain walls were found to be the cause of the high magnetization of the BFO films.

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Active eutectic brazing alloys based on certain refractory metals are produced by melting in vacuum arc or electron-beam systems with subsequent rolling of ingots into foil or by electroplating of components on titanium foil. A large number of promising brazing alloys can be produced by conventional methods because of the high hardness and brittleness of alloys or because of the need for vacuum welding sheets of refractory metals produced by hot rolling.In this work, the authors propose a technology of producing active multicomponent brazing alloys of the Ti-Nb-V, Zr-Ti-V-Fe and V-Pd-Nb, Cu-Ni-V-Ti-Zr and Fe-V-Nb systems, including explosion welding the components of the brazing alloy with the production of multilayer blanks with high strength of the joints in the layers, cold rolling of the blanks to the design thickness with intermediate 'softening' heat treatment, and subsequent diffusion annealing for equalising the chemical composition in the thickness of the brazing alloy.To decrease the nonuniformity of layer deformation and minimise the deflection of welded and rolled sheets, investigations were carried out using a symmetric system of composition of the packets.The initial thickness of the sheets-components was calculated taking into account the required chemical composition of the brazing alloy, density and dimensions of the refractory elements used. The thickness of the interlayers was varied from 0.1 to 3.0 mm, and the thickness of the welded packets from 3.4 to 11 mm. The optimum welding conditions and absence of 'dangerous' heterogeneities in the form of brittle intermetallic and chemical compounds at the layer boundaries was ensured by rational alternation of the layers of the metals taking into account their initial thickness. In particular, it was taken into account that Ti with V and Zr, and also V with Fe and Nb form a continuous series of solid solutions. The alloys of the Cu-V system are characterised only by the formation of limited solid solutions with low hardness, high-strength and ductility. The compounds of Cu and Ni with Ti, Nb with Pd and Fe are characterised by the limited initial solubility and form, at specific concentrations, intermetallic compounds with high hardness and brittleness. The hardness of the intermetallic compounds of the elements with similar chemical properties (Fe-Nb) is slightly lower at a specific ductility. 1 Removal of the powerful effect on the intermetallic compounds was achieved by selecting the optimum conditions of welding and using equipment with a given rigidity. Examples of the distribution of layers in the explosion-welded multilayer blanks of the brazing alloys are presented in Fig. 1.In the conventional methods of welding multilayered packets of metals and alloys with a thickness smaller than 1 mm, welded joints often contain defects in the form of bubbles, lack of fusion and fracture of the upper layers. 2 To protect against the nonstationary nature of detonation of the explosive substance (ES) and perturbations in the explosion products, experiments...