Introduction Nanostructured Co3O4 in thin film form may possess and demonstrate a variety of properties making the material attractive for several applications. Co3O4 has been investigated as an important electrode material [1-4], gas sensor [5, 6], catalyst [7, 8], or superhydrophobic coating [9]. Co3O4 films have demonstrated resistive switching properties potentially enabling their application in resistive random access memory devices [10, 11]. Cobalt oxide, Co3O4, containing Co 2+ and Co 3+ ions, is recognized as magnetic semiconductor material [12]. Antiferromagnetic behavior with characteristic magnetization-field curves can be demonstrated by Co3O4 nanoparticles [13]. Regarding the possible applications in spintronics, it may occur necessary to activate ferromagnetic coupling in Co3O4 nanoparticles by hybridization with foreign materials, e.g. graphene oxide [14]. Co3O4 films have been grown by oxidation of electron-beam evaporated Co layers [15], pulsed laser deposition [5, 10] chemical bath deposition [1, 6], chemical solution deposition [8, 11], hydrothermal method [2, 13], solvothermal synthesis [9], spray pyrolysis [16]

Atomic layer deposition method was employed to deposit thin films consisting of ZrO 2 and HfO 2. Zirconia films were doped with hafnia and vice versa, and also nanolaminates were formed. All depositions were carried out at 300 • C. Most films were crystalline in their as-deposited state. Zirconia exhibited the metastable cubic and tetragonal phases by a large majority, whereas hafnia was mostly in its stable monoclinic phase. Magnetic and electrical properties of the films were assessed. Un-doped zirconia was ferromagnetic and this property diminished with increasing the amount of hafnia in a film. All films exhibited ferroelectric-like behavior and the polarization curves also changed with respect to the film composition.

PbTe and Pb0.8Sn0.2Te epitaxial films on cleaved BaF2 substrates prepared by a modified hotwall technique Results are presented for below-band-gap (A~5-12 jJ.m) optical-absorption measurements at 300 and 77 K on epitaxial p-type PbTe films grown on BaF z . These results indicate a significant reduction in the absorption previously reported on PbTe epitaxial films on NaCI substrates. A few samples show an additional absorption suggestive of impurity effects. He 4 ion-backscatter spectra of these films show a surface contamination of chlorine. The results of room-temperature optical-absorption measurements on less contaminated samples agree reasonably well with bulk sample behavior. In low-carrier-concentration films (p < 10 17 cm-3 ) impurity effects appear to eliminate any temperature dependence of the absorption. The presence of the surface contamination does not affect the dc transport or refractive-index properties.

CoFe 2 O 4 nanoparticles with 3-30 nm in diameter were synthesized by sol-gel method. The particles were spread as a solid discontinuous layer over planar silicon and TiN substrates by spin coating and covered by 15 nm thick ZrO 2 films by atomic layer deposition. Crystal structures distinctively characteristic of CoFe 2 O 4 and ZrO 2 constituents were preserved. The nanocomposite CoFe 2 O 4 -ZrO 2 layers demonstrated dielectric polarization, saturative magnetization, and implications of resistive switching behavior. Behavior most clearly attributed to memory materials was observed in the field admittance characteristic with two distinct states in susceptibility of the nanocomposite. There is permanent and growing interest in complex compound materials for a variety of applications in which the components tailor their best structural, mechanical, optical or electronic properties making the material versatile for the planned applications. Metal oxide based layered systems can demonstrate a variety of resistive switching, ferroelectric, ferromagnetic and other properties useful in prospective devices.1 Cobalt-iron-oxygen ternary system has been of considerable interest, driven perhaps by the necessity of use it as a constituent compound in more complex structures exploited in solid oxide fuel cells. 2 Cobalt ferrite has been studied 3 as an attractive magnetic material suited to magneto-optical recording, integrated optics, or waveguides, due to its potential combination of semiconducting and magnetic properties including high coercivity, anisotropy, and magnetostriction.CoFe Regarding other 3D structures based on cobalt ferrite, Co x Fe 3−x O 4 magnetic thin films have been grown on the pore walls of alumina membranes by atomic layer deposition. 17 Cobalt ferrite in thin film form has also been prepared by spray pyrolysis using cobalt and iron nitrate precursors.18 Magnetization-field or Kerr loops with certain coercive force has earlier been recorded in CoFe 2 O 4 particles [3][4][5][6]8,10,14,16 and thin films, 18 in most cases at room temperature. Ferromagnetic CoFe 2 O 4 particles have been added to YBa 2 Cu 3 O 7-δ thin films to enhance flux pinning in potentially superconducting materials which, however, led to the formation of Y(Fe,Co)O 3 , leaving the host material yttrium-deficient. 19 On the other hand, dilute Fe and Co codoping into ZrO 2 has resulted in ferromagnetic behavior at room temperature for annealing temperatures above 900• C, suggesting that partial formation of secondary phases, such as cobalt ferrite, promoted ferromagnetism. 20 Very small CoFe 2 O 4 particles with diameter 4-6 nm alone have also demonstrated magnetization decreasing toward higher temperatures and have thus been described as superparamagnetic. 6,9 Coercive field decreased substantially with increasing temperature, although saturative magnetization could be achieved at room temperature as well. CoFe 2 O 4 particles embedded in SiO 2 /ZrO 2 host matrix have been studied and characterized as magneto-optical isolators and desc...