Browsing by Author "Mukubwa, Abel"

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    Energy of plasmon-mediated boson-fermion pair condensate in high temperature superconductors
    (Physica B: Condensed Matter, 2021-10-01) Mukubwa, Abel; Makokha, John Wanjala
    Interaction between particles in condensate state is nontrivial in understanding charge pairing that defines high-temperature superconductivity . A Bose-Einstein Condensate (BEC) of a non-zero-momentum Cooper pair constitutes a composite boson. A two-component electronic BEC - bosons and fermions -harbours some properties that are closely related to those of high temperature superconductors. We demonstrated that quantum coherence of a boson-fermion condensate is controlled by plasmons. A binary electronic system has an associated response function, given by the zero of longitudinal dielectric function. The response function has both long and short-wavelength branches, at least in layered superconductors. Coulomb screening of bosons by the electron cloud, in the long-wavelength branch, drives plasmon mediation in boson-fermion (BF) pairing. This study reveals that: the attractive potential in boson-fermion pair condensate (BFPC) is anisotropic, the magnitude of collective BEC excitations is in the order of an energy gap and that boson-fermion coherence under plasmon-mediation occurs at 10-9 m.
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    Gauge-Invariant Wigner Function Extended to High Temperature Superconductivity
    (Social Science Research Network, 2021-11-02) Mukubwa, Abel; Makokha, John Wanjala
    The realization of gauge-invariant Wigner function (GIWF) has revolutionized studies on quantized and classical electromagnetic fields and has been adapted to a magnetostatic phenomenon in superconducting systems. We apply the quantum fluid moment hierarchy equations in solving the conservative moment equation of the gauge-invariant Wigner operator. The results show that the lower critical field (𝐻𝑐1), the vortex radius (𝑟0) and the penetration depth (𝜆) show dependence on Cooper pair excitation energy (𝐸𝑘).
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    Sommerfeld’s Coefficient of a Boson-Fermion Pair Condensate in High Temperature Superconductors
    (Social Science Research Network, 2021-12-29) Mukubwa, Abel; Masinde, Fred Wekesa; Makokha, John Wanjala
    High temperature superconductivity has shown dependence on the interaction between a finite momentum Cooper-pair boson and a fermion. The occurrence of a superconducting energy gap in cuprates is defined by collective excitation of boson-fermion pair condensates (BFPC) above the ground state. The ground state energy of the system represents its total internal and has been used to determine Sommerfeld’s coefficient of a BFPC in high temperature superconductor’s. Atypically, the study is furthered by linking the theory to experiments, through extrapolations, leading to high-precision results both in cuprates and iron-based superconductors. For instance, the Sommerfeld’s coefficients of the model in YBa2Cu3O7 and Ca0.33Na0.67Fe2As2 are found to be 30.36mjmol-1 K-2 and 114.1mjmol-1 K-2 respectively while the empirical ranges in these materials are 30±5 mjmol-1 K-2 and 105±5 mjmol-1 K-2 respectively.
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    Sommerfeld’s Coefficient Of Boson-Fermion Pair Condensate In Optimally-Doped Cuprates
    (Journal of Multidisciplinary Engineering Science and Technology, 2021-12-05) Mukubwa, Abel; Masinde, Fred Wekesa; Makokha, John Wanjala
    High temperature superconductivity has shown dependence on the interaction between a finite momentum Cooper-pair boson and a fermion. The occurrence of a superconducting energy gap in cuprates is defined by collective excitation of boson-fermion pair condensates (BFPC) above the ground state. The ground state energy of the system represents its total internal and has been used to determine Sommerfeld’s coefficient of a BFPC in high temperature superconductor’s. Atypically, the study is furthered by linking the theory to experiments, through extrapolations, leading to high-precision results both in cuprates and ironbased superconductors. For instance, the Sommerfeld’s coefficients of the model in YBa2Cu3O7 and Ca0.33Na0.67Fe2As2 are found to be 𝟑𝟎.𝟑𝟔𝐦𝐉𝐦𝐨𝐥−𝟏𝐊−𝟐 and 𝟏𝟏𝟒.𝟏𝐦𝐉𝐦𝐨𝐥−𝟏𝐊−𝟐 respectively while the empirical ranges in these materials are 𝟑𝟎±𝟓𝐦𝐉𝐦𝐨𝐥−𝟏𝐊−𝟐 and 𝟏𝟎𝟓± 𝟓 𝐦𝐉𝐦𝐨𝐥−𝟏𝐊−𝟐 respectively