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Item Higher order elastic constants and generalized Gruneisen parameters of elastic waves and low temperature thermal expansion of gadolinium(Springer, 1996-12) Nair, Sindhu S.Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in gadolinium. The higher order elastic constants are used to find out the generalized Gruneisen parameters of the elastic waves propagating in different directions in gadolinium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.Item Fourth order nonlinear elastic coefficients of hexagonal close packed lattice(Elsevier, 1996-09) Nair, Sindhu S.The expressions for the fourth-order elastic constants of a hexagonal close packed lattice is derived using the sublattice displacements to the second order in strains. These expressions together with the expressions for the second- and third-order elastic constants have been used to obtain the higher order nonlinear elastic coefficients in some hexagonal metals. These expressions are used to find the second-order, third-order and fourth-order elastic constants of cadmium. The pressure derivatives of their elastic constants are also obtained. The results obtained are compared with the available experimental results.Item Higher order elastic constants and second pressure derivatives of zirconium(IAEA, 1997) Nair, Sindhu S.Expressions for the higher order elastic constants are derived using the sublattice displacements to the second degree in strains. These expressions together with the expressions for the second and third order elastic constants have been used to obtain the higher order elastic constants and the pressure derivatives to second order elastic constants of hexagonal zirconium. The results obtained are compared with the reported values. The second pressure derivatives of zirconium are also reportedItem Higher Order Elastic Constants and Generalized Gruneisen Parameters of Elastic Waves and Low Temperature Thermal Expansion of Titanium(Elsevier, 1997-02) Nair, Sindhu S.The expressions for the 19 fourth order elastic constants, 10 third order elastic constants, and 6 second order elastic constants of a solid are derived using the method of homogenous deformation with interactions extending up to second neighbors using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in titanium. Titanium belongs to the hexagonal class of crystals. The higher order elastic constants are used to find the generalized Gruneisen parameters of the elastic waves propagating in different directions in titanium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.Item Higher order elastic constants and generalised gruneisen parameters of elastic waves and low temperature thermal expansion of dysprosium(Elsevier, 1997-12) Nair, Sindhu S.The expressions for the 19 fourth order elastic constants, 10 third order elastic constants and six second order elastic constants are derived using the method of homogenous deformation with interactions extending up to second neighbours using the sublattice displacements to the second degree in strains. These expressions are used to obtain the higher order elastic constants and their pressure derivatives in dysprosium. Dysprosium belongs to the hexagonal class of crystals. The higher order elastic constants are used to find out the generalised Gruneisen parameters of the elastic waves propagating in different directions in dysprosium. The Brugger gammas are evaluated and the low temperature limit of the Gruneisen gamma is obtained. The results are compared with the available reported values.Item Third-order elastic constants and low-temperature lattice thermal expansion of the high-temperature structural material TiAl(IOP, 2001) Nair, Sindhu S.We have derived the expressions for the 12 third-order elastic constants for a tetragonal system by the method of homogeneous deformation which are used to determine the third-order elastic constants of TiAl. These third-order elastic constants are used to determine the low-temperature limit of the volume thermal expansion of TiAl. The value of C333 was calculated to be a high value. The high value of the third-order elastic constant C333 shows a marked anisotropy in the crystal. The low-temperature limit is found to be negative, indicating a negative volume thermal expansion down to zero kelvin.Item Micromagnetic simulations of the domain structure and the magnetization reversal of Co50Ni50/Pt multilayer dots(Elsevier, 2002-01) Nair, Sindhu S.The domain structure and the switching field of Co50Ni50/Pt multilayer dots, prepared by laser interference lithography, were micromagnetically simulated. The simulations were carried out with a three-dimensional simulation package, optimized for large-scale problems. The single-domain state is the lowest energy state for dots with a diameter below 75 nm. The switching field was computed by using suitable minimization techniques, and was used to analyze the effect of size, dot shape and edge defects.Item A Photoemission study of CoO films on Au (111) Surface Science(Elsevier, 2003-09) Nair, Sindhu S.Angle-resolved ultraviolet photoemission spectroscopy has been used to study thin layers of Co and CoO on an Au(1 1 1) substrate. A bulk-like CoO layer was obtained for a nominal coverage of 7 ML Co, with Co evaporated in an oxygen atmosphere of 10−4 Pa and the Au(1 1 1) substrate at 350 K. Low-energy electron diffraction of this layer exhibits a (1 × 1) structure, indicating an unreconstructed CoO(1 1 1) surface. Considering the instability of a bulk-like terminated CoO surface, we assume stabilization by OH termination. At low coverage, the CoO layer is oxygen deficient and exhibits metallic character. For the bulk-like CoO layers we found band-like oxygen states and no detectable dispersion for the states near the Fermi edge, which is in agreement with previous investigations of single-crystalline CoO.Item Growth mechanism and angle-resolved photoemission spectra of cobalt oxide (CoO) thin films on Ag(1 0 0)(Elsevier, 2004-09) Nair, Sindhu S.Using Auger electron spectroscopy we have studied the growth of cobalt oxide on Ag(1 0 0) substrate at different substrate temperatures (25, 170 and 250 °C). The films grown at 170 °C substrate temperature were found to grow closest to a layer-by-layer growth mode. In order to experimentally investigate the electronic structure of the CoO films angle-resolved UV photoelectron spectra were recorded for a 10 ML CoO film that are discussed and compared with available experimental results.Item Generalized Grüneisen parameters and low temperature limit of lattice thermal expansion of cadmium and zirconium(Springer, 2006-09) Nair, Sindhu S.The generalized Grüneisen parameters (γ′ j ) and (γ″ j ) for cadmium and zirconium were calculated from the second- and third-order elastic constants to determine the low temperature limit of the volume thermal expansion of these metals of hexagonal symmetry. The low temperature limit of cadmium and zirconium was calculated to be positive values indicating a positive volume expansion down to 0 K even though many Grüneisen gammas were found to be negative.