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The present work reports the effects of 120 MeV Au9+ on structural and electronic properties of polycrystalline SnO2 films of about 170 nm thickness prepared by spin-coating. 119Sn Mössbauer measurements are used to probe the electronic properties. The observed isomer-shift values clearly indicate Sn4+ for the pristine sample and its progressive reduction to Sn2+ and eventually to the metallic Sn state at higher fluence values. These observations are corroborated by x-ray diffraction, Raman, and x-ray photo-electron spectroscopy measurements. The x-ray diffraction measurements indicate the complete amorphization of the tin oxide phase, while the recrystallization of the metallic Sn phase with irradiation. The optical bandgap is observed to vary with ion beam irradiation. The observations indicate the possibility of tuning the electronic configuration of Sn in tin oxide thin films with swift heavy ion beam irradiation, and the results are explained in terms of the thermal-spike model of swift heavy ion irradiation. [ABSTRACT FROM AUTHOR]

Swift heavy ions induced structural and magnetic modifications of Co/Ti multilayers have been studied with 120 MeV Ag9+ ions at different ion fluences. The decrease in 1st Bragg peak intensity of X-ray reflectivity spectra confirms an increase in Co-Ti mixing at the interfaces, whereas X-ray diffraction (XRD) measurements reveal amorphization of the crystalline Co layer. XRD also indicates a shift in peak position towards a lower angle, confirming the development of tensile stress upon irradiation whereas an increase in the peak width suggests the reduction in the grain size. Vibrating sample magnetometer measurements show a reduction in Mr/Ms due to Co-Ti interface mixing and formed bcc-Co3Ti metastable phase. The X-ray absorption fine structure (XAFS) technique has been utilized to obtain variation in Co-Co and Co-Ti bond distances as a function of ion fluences. Quantitative estimation of Co3Ti phase generated due to ion irradiation has also been obtained using Co K-edge XAFS fitting. [ABSTRACT FROM AUTHOR]

The quality of organic semiconductor tris-(8-hydroxyquinoline)aluminum (Alq3) thin films, deposited at the rate of 5.0 Ĺ s−1, 2.5 Ĺ s−1, and 1.0 Ĺ s−1 respectively, have been investigated using x-ray reflectivity (XRR) and grazing incidence small angle x-ray scattering (GISAXS) studies. While XRR provides information about structural details, GISAXS provides information about the morphology of the films. The film quality is very good with a surface roughness of only 8 Ĺ. The electron density of the film increases from 0.39 e Ĺ−3 to 0.43 e Ĺ−3 due to reduction of growth rate from 5 Ĺ s−1 to 1 Ĺ s−1. The higher electron density (0.43 e Ĺ−3) of the film deposited at the lower deposition rate (1 Ĺ s−1) indicates the presence of less defects and/or porosity in the film. Average separation between pores increases from 200 Ĺ to 500 Ĺ and simultaneously pore depth decreases from 300 Ĺ to 120 Ĺ due to reduction of growth rate from 5 Ĺ s−1 to 1 Ĺ s−1. The mixing between Alq3 and Co at the Alq3/Co interface and diffusion of Co into Alq3 layer through Co/Alq3 interface have been studied by combined XRR and grazing incidence x-ray standing wave (GIXSW) measurements for the three Alq3/Co/Alq3/W/Si multilayers in which Alq3 films were deposited at the above mentioned three different rates. It is found that there is about 30 Ĺ thick (∼ two monolayer of Alq3) mixing region at the Alq3/Co interface in three multilayer samples, which suggests that mixing at this interface is independent of the growth rate of Alq3 films. The depth of diffusion of Co into Alq3 through Co/Alq3 interface reduces from 300 Ĺ to 160 Ĺ due to the reduction of deposition rate from 5 Ĺ s−1 to 1 Ĺ s−1. This study suggests that by controlling the growth rate of Alq3, porosity as well as the diffusion of ferromagnetic Co in an organic semiconductor Alq3 can be reduced, which plays an important role in the performance of organic spin valve devices. [ABSTRACT FROM AUTHOR]

Aging and de-aging behavior of un-doped polycrystalline BaTiO3(BTO) is studied with the P-E measurements. The double hysteresis (P-E) loop is observed for the aged sample and it is observed that the relationship between the aging time and the developed internal bias field is similar to as that of reported for acceptor doped BTO and other ferroelectric materials in literature. However, the relaxation rates are quite different as compared to that of acceptor doped BTO. This is explained in terms of defect concentration. The de-aging behaviour is studied with different methods viz., thermal relaxation, combined use of temperature and applied electric field. Heating the sample slightly above its TCand cooling in the presence of external applied dc- field is observed to completely remove the pinching and bring the internal bias field to zero. [ABSTRACT FROM AUTHOR]

Present study provides an insight of tailoring magnetic properties (static and dynamic) driven by structural modifications, with controlled incorporation of Ta in soft magnetic CoFeB films. Unlike conventional thermal annealing, stress induced in-plane uniaxial magnetic anisotropy of CoFeB have observed to be release with incorporation of Ta, as confirmed from in-plane rotation dependent magneto-optical Kerr effect (MOKE). Increasing atomic percent of Ta in CoFeB is accompanied with decreasing saturation magnetization of soft-magnetic layer and film densification, as confirmed from polarized neutron and X-ray reflectivities. Ferromagnetic resonance (FMR) confirms the reduction of effective magnetization of the samples with Ta incorporation, with rise of damping parameter because of increasing magnetic inhomogenities. Further, the effect of vacuum annealing on these films has been investigated. Post annealing measurements suggest rapid elimination of magnetic anisotropy for Ta doped CoFeB films. Annealing at a temperature beyond CoFeB crystallization temperature results in an increase of magnetization, relative to as-prepared samples, amplitude of which modifies with incorporated Ta concentration. Such enhancement is accompanied with the structural changes as confirmed from X-ray diffraction (XRD) measurements, resulting an increase of magnetic coercivity. The results are important in view of tailoring the functional properties of CoFeB films for wide range of applications. • As-deposited CoFeB film exhibits stress induced uniaxial magnetic anisotropy (UMA). • Incorporation of Ta in CoFeB results in rapid elimination of UMA with annealing. • Damping parameter (α) increases with increasing Ta incorporation in CoFeB. • Effective magnetization (Ms) decreases with increasing Ta concentration in CoFeB. • Post annealing measurements suggest tailoring of Ms and α, which varies with Ta at%. [ABSTRACT FROM AUTHOR]