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Local order, electronic structure, and magnetic properties of Co-doped VOx films electrochemically grown onto Si are investigated. The films are studied by means of X-ray absorption spectroscopy (XAS) and magnetic measurements. Freshly made films have V2O5·n(H2O) structure with vanadium valence close to +5. XAS data show that insertion of Co in the films does not affect the close environment around V, when compared to the undoped sample, even varying the concentration of Co by ten times. The site symmetry of Co dopant atoms in the films is consistent with an octahedral coordination where Co is surrounded by six oxygen atoms, as supported by X-ray absorption near-edge structure simulations. Furthermore, there is no evidence of the presence of metallic cobalt (Co0) in the films. The incorporation of small amounts of Co turns ferromagnetic undoped samples into paramagnetic ones. The net magnetic moment per unit volume initially decreases with the incorporation of Co and enhances for higher concentrations. Such behavior is consistent with an O vacancy reduction process driven by the insertion of Co in the films. [ABSTRACT FROM AUTHOR]

In this work, we study the local atomic and electronic structures as well as oxygen-vacancy-induced magnetic properties of electrodeposited V2O5 films. Unlike stoichiometric V2O5, which is a diamagnetic lamellar semiconductor, our oxygen-defective V2O5 films are ferromagnetic at room-temperature and their saturation magnetization decreases with air exposure time. X-ray absorption spectroscopy was used to monitor the aging effect on these films, revealing that freshlymade samples exhibit only local crystalline order, whereas the aged ones undoubtedly show an enhancement of crystallinity and coordination symmetry. The mean number of oxygen atoms around V tends to increase, indicating a decrease of oxygen vacancies with time. Concurrently with the decrease of oxygen vacancies, a loss of saturation magnetization is also observed. Hence, it can be concluded that the ferromagnetism of the V2O5 films originates from a vacancy-induced mechanism, confirming the universality of this class of ferromagnetism. [ABSTRACT FROM AUTHOR]

This work reports the effect of Mn, Fe, Co, and Cu low doping (∼3 at. %) on the ferromagnetic behavior of oxygen-defective CeO2-δ films electrodeposited on SiO2/Si(001). Our results indicate that the incorporation of a small number of 3d dopants with unoccupied outermost atomic orbitals, presumably magnetically active, strongly perturb the ferromagnetic ground-state associated with the network of electron clouds surrounding oxygen vacancies. As a consequence, a strong loss of magnetization occurs and saturation magnetization becomes uncorrelated with number of oxygen vacancies. [ABSTRACT FROM AUTHOR]

Structural differences between pure and LiCF3SO3-doped amorphous WO3 thin films were studied by Raman spectroscopy and X-ray photoelectron spectroscopy analysis. Based on our interpretation of reports in the literature on Raman spectra of WO3 thin films, we found that the LiCF3SO3-doped amorphous WO3 film presented greater amounts of oxygen vacancies, W+4 valence state and W+6=O surface vibration modes. These structural differences served as the basis to make inferences about the dissimilarities also found in the kinetic coloration observed during the electroinsertion reaction, focusing particularly on the dynamics of Li+ insertion into the two different structures. [ABSTRACT FROM AUTHOR]

The thermal evolution of a ZnSe epilayer grown by molecular beam epitaxy on GaAs(001) has been studied by high resolution x-ray diffraction as well as photoelectron and Raman spectroscopies. Sequential annealing of a relaxed epilayer reveals a fast migration of Ga towards the ZnSe cap layer with a significant accumulation of As atoms near the ZnSe-reacted interface. A Ga[sub 2]Se[sub 3] compound appears as a predominant byproduct whereas Zn atoms are probably diffusing from the reacted interface into the GaAs substrate. [ABSTRACT FROM AUTHOR]

We report the chemical stability of the hybrid Fe/ZnSe/GaAs heterostructure prepared by molecular-beam epitaxy. Analyses of photoemission spectra show a remarkable chemical stability of the Fe/ZnSe(001) interface up to 380 °C, where the effective disruption of the heterostructure occurs, together with the appearance of Ga atoms near the film surface. This suggests that the ZnSe/GaAs interface is surprisingly less stable than the Fe/ZnSe one. [ABSTRACT FROM AUTHOR]

Reports on the successful epitaxial growth of iron/copper superlattices on silicon(111) wafers at room temperature. Characterization of the superlattices; High angle diffraction results of the samples; Conversion electron Mössbauer spectra for the iron/copper superlattices.

Presents a study that investigated the thermal evolution of reactively sputtered iron nitride (FeN) thin films. Magnetic and metallurgical properties of the Fe-N system; Experimental techniques used; Comparison of the decomposition temperature of thin film samples and bulk samples.

Studies the compositional and magnetic properties of iron nitride thin films. Overview of iron-nitrogen system; Methodology of the study; Discussion on the results of the study.

Presents a study which reported successful and unexpected epitaxial growth of copper and calcium fluorine[sub2] bilayers on hydrogen terminated silicon wafers by thermal evaporation. Background on studies on the growth of epitaxial thin films; Method used in analyzing the orientation of the bilayer in the direction perpendicular to the film plane; Results of the rocking curve experiment.