Browsing by Author "Wainstein, D. L."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    The confinement of phonon propagation in TiAlN/Ag multilayer coatings with anomalously low heat conductivity
    (American Institute of Physics, 2016-06-03) Kovalev, Anatoly I.; Wainstein, D. L.; Rashkovskiy, A. Y.; Gago, R.; Soldera, F.; Endrino, José L.
    TiAlN/Ag multilayer coatings with a different number of bilayers and thicknesses of individual layers were fabricated by DC magnetron co-sputtering. Thermal conductivity was measured in dependence of Ag layer thickness. It was found anomalous low thermal conductivity of silver comparing to TiAlN and Ag bulk standards and TiAlN/TiN multilayers. The physical nature of such thermal barrier properties of the multilayer coatings was explained on the basis of reflection electron energy loss spectroscopy. The analysis shows that nanostructuring of the coating decreases the density of states and velocity of acoustic phonons propagation. At the same time, multiphonon channels of heat propagation degenerate. These results demonstrate that metal-dielectric interfaces in TiAlN/Ag coatings are insurmountable obstacles for acoustic phonons propagation.
  • Thumbnail Image
    ItemOpen Access
    Features of electronic and lattice mechanisms of transboundary heat transfer in multilayer nanolaminate TiA1N/Ag coatings
    (Nature Publishing Group, 2017-12-06) Kovalev, Anatoly I.; Wainstein, D. L.; Vakhrushev, V. O.; Gago, R.; Soldera, F.; Endrino, José L.; Fox-Rabinovich, German S.; Veldhuis, Stephen C.
    Plasmon resonance heterogeneities were identified and studied along Ag and TiAlN layers within a multilayer stack in nanolaminate TiAlN/Ag coatings. For this purpose, a high-resolution plasmon microscopy was used. The plasmons intensity, energy, and depth of interface plasmon-polariton penetration were studied by scanning reflected electron energy loss spectroscopy. The heat conductivity of such metal-insulator-metal (MIM) nanolaminate coatings was measured by laser reflectometry. Dependencies of thermal conductivity coefficient of coatings, MIM interfaces, and resistivity of Ag layers as a function of the Ag-TiAlN bilayer thickness were calculated on the basis of experimental data. The contribution of plasmon resonance confinement to the abnormal lower thermal conductivity in the MIM metamaterial with Ag layer thickness below 25 nm is discussed. In particular, the results highlight the relevant role of different heat transfer mechanisms between MI and IM interfaces: asymmetry of plasmon-polariton interactions on upper and lower boundaries of Ag layer and asymmetry of LA and TA phonons propagation through interfaces.
  • Thumbnail Image
    ItemOpen Access
    Interface-induced plasmon nonhomogeneity in nanostructured metal-dielectric planar metamateria
    (Hindawi Publishing Corporation, 2015) Kovalev, Anatoly I.; Wainstein, D. L.; Rashkovskiy, A. Y.; Gago, R.; Soldera, F.; Endrino, José L.; Fox-Rabinovich, German S.
    Transformations of the electronic structure in thin silver layers in metal-dielectric (TiAlN/Ag) multilayer nanocomposite were investigated by a set of electron spectroscopy techniques. Localization of the electronic states in the valence band and reduction of electron concentration in the conduction band was observed. This led to decreasing metallic properties of silver in the thin films. A critical layer thickness of 23.5 nm associated with the development of quantum effects was determined by X-ray photoelectron spectroscopy. Scanning Auger electron microscopy of characteristic energy losses provided images of plasmon localization in the Ag layers. The nonuniformity of plasmon intensities distribution near the metal-nitride interfaces was assessed experimentally.