Interdiffusion in Fe-Pt multilayers

Fe/Pt multilayers with modulation periods Lambda=24.1 +/- 0.2 and 37.2 +/- 0.1 A and [110]parallel to[111] bcc-fcc texture were fabricated by magnetron sputtering on thermally oxidized Si wafers. The structural evolution of the multilayers with annealing temperature in the range of 300-600 K was studied by in situ x-ray diffraction (XRD) and x-ray reflectivity. Two temperature regimes were found from the XRD data. Below 534 +/- 4 K slow, short-range diffusion is observed without significant broadening of the satellite peaks or changes in the texture. Above 534 K fast, long-range diffusion is observed accompanied by significant broadening of the satellites and rapid increase of the misorientations of the grains. The multilayers crystallize at about 583 K into the tetragonal FePt phase with a small degree of ordering and strong [111] texture. The transition resembles a first-order phase transition with a critical exponent beta=0.48 +/- 0.01 which practically does not depend on Lambda. The bulk interdiffusion coefficient, determined from the decay of the -1 satellite of the (001) Bragg peak of the multilayers, can be expressed in Arrhenius form as D(T)=(1.37 +/- 0.26)x10(-6) exp(-1.7 +/- 0.6/k(B)T) m(2)/s. The gradient-energy coefficient k, entering the Cahn-Hilliard diffusion equation [Acta Metallurg. 9, 795 (1961), 10, 179 (1962); J. Chem. Phys. 28, 258 (1959)], was estimated from the Lambda dependence of the diffusion coefficient to be (-6.8 +/- 0.2)x10(7) eV/cm. (c) 2006 American Institute of Physic

Structure of PtFe/Fe double-period multilayers investigated by X-ray diffraction, reflectivity, diffuse scattering and TEM

Double-period [(Pt 1.7 nm/Fe 0.9 nm)(5)Fe(tFeA(2))](8) and [(Pt 1.8 nm/Fe 0.6 nM)(5)Fe(t(Fe2))](8) multilayers with different thickness t(Fe2) (between 0.23 and 4.32 nm) of the additional Fe layers, prepared by combinatorial sputter deposition, show differences in the mosaic spread and the vertical interfacial roughness when deposited on native or thermally oxidised Si wafers. Simulations of the wide-angle X-ray scattering intensities revealed the presence of interdiffusion in the (Pt/Fe)(5) bilayers and systematic variations of the grain sizes, perpendicular to the film surface, as well as the rms variations of the two superlattice periods with the total film thickness. A comparison of omega-rocking scans shows an increase of the correlated vertical roughness of the (Pt/Fe)5 multilayers with the total multilayer thickness. (c) 2006 Elsevier B.V. All rights reserve

Structure of Pt-Fe/Fe double-period multilayers investigated by X-ray diffraction, reflectivity, diffuse scattering and TEM

Double-period [(Pt 1.7 nm/Fe 0.9 nm)(5)Fe(tFeA(2))](8) and [(Pt 1.8 nm/Fe 0.6 nM)(5)Fe(t(Fe2))](8) multilayers with different thickness t(Fe2) (between 0.23 and 4.32 nm) of the additional Fe layers, prepared by combinatorial sputter deposition, show differences in the mosaic spread and the vertical interfacial roughness when deposited on native or thermally oxidised Si wafers. Simulations of the wide-angle X-ray scattering intensities revealed the presence of interdiffusion in the (Pt/Fe)(5) bilayers and systematic variations of the grain sizes, perpendicular to the film surface, as well as the rms variations of the two superlattice periods with the total film thickness. A comparison of omega-rocking scans shows an increase of the correlated vertical roughness of the (Pt/Fe)5 multilayers with the total multilayer thickness. (c) 2006 Elsevier B.V. All rights reserve

Interdiffusion in Fe/Pt Multilayers: In situ high temperature synchrotron radiation reflectivity study

Thermal annealing of Fe/Pt multilayers (ML) is reported to reduce significantly the formation temperature of FePt hard magnetic thin films. The transformation mechanisms of [Fe 1.38 nm/Pt 2.24 nm](50) ML, prepared by magnetron sputtering, is investigated in the present communication by high temperature X-ray reflectivity using synchrotron radiation. Complete degradation of the ML periodic structure is observed at about 610 K. The variation with annealing temperature of the intensity of the first Bragg peak, the correlated vertical roughness, and the lateral correlation length of the ML show that the ML transform in two stages with a cross-over temperature of about 515 +/- 15 K. This behavior cannot be simply explained by the change in the measured interdiffusion coefficient below and above the cross-over temperature, suggesting the formation of FePt nanograins along the interfaces

Fabrication of chemical templates via selective laser-induced desorption of hexadecanethiol self-assembled monolayers

A nonlinear photothermal laser patterning technique for rapid fabrication of chemical templates is demonstrated. Hexadecanethiol monolayers on Au-coated Si substrates are processed at lambda = 532 nm, a 1/e(2) spot diameter of d(1/e)(2) = 2.8 mu m and ambient conditions. Local laser irradiation at high laser powers and short irradiation times in the micro-/millisecond range induces desorption of thiol molecules. The laser-depleted areas are backfilled with mercaptohexadecanoic acid in order to build up chemical templates. Atomic force microscopy, scanning electron microscopy and scanning Auger electron spectroscopy are used for characterization of these templates. In agreement with a selective laser process, the results indicate the formation of flat chemical patterns with well-defined boundaries. Complementary condensation experiments demonstrate the functionality of the patterns as hydrophilic/hydrophobic templates. In particular, upon decreasing the temperature below the dew point, selective formation of water droplets on the backfilled areas is observed. (C) 2013 Elsevier B. V. All rights reserved

Malonate complexes of dysprosium: synthesis, characterization and application for LI-MOCVD of dysprosium containing thin films

A series of malonate complexes of dysprosium were synthesized as potential metalorganic precursors for Dy containing oxide thin films using chemical vapor deposition (CVD) related techniques. The steric bulkiness of the dialkylmalonato ligand employed was systematically varied and its influence on the resulting structural and physico-chemical properties that is relevant for MOCVD was studied. Single crystal X-ray diffraction analysis revealed that the five homoleptic tris-malonato Dy complexes (1-5) are dimers with distorted square-face bicapped trigonal-prismatic geometry and a coordination number of eight. In an attempt to decrease the nuclearity and increase the solubility of the complexes in various solvents, the focus was to react these dimeric complexes with Lewis bases such as 2,2'-biypridyl and pyridine (6-9). This resulted in monomeric tris-malonato mono Lewis base adduct complexes with improved thermal properties. Finally considering the ease of synthesis, the monomeric nature and promising thermal characteristics, the silymalonate adduct complex [Dy(dsml)(3)bipy] (8) was selected as single source precursor for growing DySixOy thin films by liquid injection metalorganic chemical vapor deposition (LI-MOCVD) process. The as-deposited films were analyzed for their morphology and composition by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Rutherford backscattering (RBS) analysis and X-ray photoelectron spectroscopy