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Subject: Physics × End date: 2009 × Start date: 2004 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Study of electrical and magnetic properties of cobalt based metallic glasses and composite material
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2005-07) Agrawal, Rati; Kushwaha, R.P.S.
    There are many materials of commercial importance; composite materials and metallic glasses are two such important materials among them. Wide variety of technological and industrial applications of these materials motivates the present work. Cobalt based metallic glass of nominal composition Co60B12Si12Fe4Mo2Ni1 and cobalt based composite material prepared by varying concentration of cobalt metal powder in plaster of paris was used for investigating their electrical and magnetic properties. For cobalt based composite material change in A.C. magnetic susceptibility with both frequency and concentration have been taken into account. Similarly temperature and concentration dependence of electrical resistivity of composite material was investigated. From experimental results obtained, A.C. magnetic susceptibility was found to decrease with frequency for all concentrations and increase in susceptibility was observed when plotted with concentration. when electrical resistivity of cobalt based composite material was investigate for its temperature dependence, slight decrease in resistivity or a dip was observed for all the concentrations i.e. for all the samples with different concentrations of cobalt metal powder in plaster of paris. Energy losses in the samples were also measured by studying their hysteresis loops for two different frequencies.
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    ThesisItemOpen Access
    Study of the role of pair transfer processes on isotope effect in superconducting TTF[Ni(dmit)2]2 systems
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2004-06) Pant, Manju; Ajay
    In the present investigation, we have studied the role of interband pair transfer processes on isotope effect in layered TTF[Ni(dmit)2]2 systems. For this purpose we have considered two chain Hubbard model that includes the intra and intermolecular vibrations in the presence of electron Coulomb energy and the electron transfer energy between the chains. Such a model calculations will be applicable for the organic superconductors where molecular layered structures are available. We obtained the expressions for the superconducting order parameter, transition temperature and finally the isotope effect coefficient ( ) using double time Greens’s function equations of motion technique within BCS mean field approximation. Finally the numerical analysis show that isotope effect coefficient ( ) depends on the intra and interlayer molecular vibrations, the pair transfer processes and also on the superconducting transition temperature (Tc) in layered organic superconductors like TTF[Ni(dmit)2]2 . On the basis of our model calculations we have predicted the effects of the pair transfer processes, the density of states at Fermi level and the chemical pressure on the isotope effect coefficient which need to be tested through rigorous experimental investigations on these systems.