Anita Kumari

Infrastructure financing and development

This paper conducts a comprehensive review of the literature published between 1989 and 2015 on infrastructure and related issues. The articles are classified and presented on the basis of publication source, publication year, country of origin, research methodology and focus area. The review reveals that most of the articles on infrastructure and related issues were published during the period 2010 through 2012. Furthermore, most studies are empirical in nature and the majority of the studies focus on infrastructure financing. Another key finding is that most of the studies deemed publicprivate partnerships to be the preferred source of infrastructure financing. The review offers a better understanding of infrastructure and related issues, and the position of existing research. The review also highlights the areas that are relatively less explored. Academicians, researchers and policy makers may use these observations as guidelines to conduct further investigations of infrastructure and related issues.

Superconducting gap anisotropy and d-wave pairing in YBa2Cu3O7−δ

Considering Born–Mayer–Huggins potential as a most suitable potential to study the dynamical properties of high-temperature superconductors (HTS), the many-body quantum dynamics to obtain phonon Green’s functions has been developed via a Hamiltonian that incorporates the contributions of harmonic electron and phonon fields, phonon field anharmonicities, defects and electron–phonon interactions without considering BCS structure. This enables one to develop the quasiparticle renormalized frequency dispersion in the representative high-temperature cuprate superconductor YBa2Cu3O7−δ. The superconducting gap shows substantial changes with increased doping. The in-plane gap study revealed a v-shape gap with a nodal point along kx = ±ky direction for optimum doping (δ = 0.16) and the nodal point vanished in underdoped and overdoped regimes. The dx2−y2 pairing symmetry is observed at optimum doping with the presence of s or dxy components ( < 3%) in underdoped and overdoped regimes.

Renormalized modes in cuprate superconductors

The renormalized mode frequencies are obtained with the help of quantum dynamical approach of many body phonon Green’s function technique via a general Hamiltonian (excluding BCS Hamiltonian) including the effects of phonons and electrons, anharmonicities and electron-phonon interactions. The numerical estimates have been carried out to study the renormalized mode frequency of high temperature cuprate superconductor (HTS) YBa2Cu3O7-δ using modified Born-Mayer-Huggins interaction potential (MBMHP) best applicable to study the dynamical properties of all HTS.

In-plane and cross-plane thermal conductivity in La2-xSrxCuO4

The problem of heat transport anisotropy in layered cuprate high temperature superconductors (HTS) has been investigated in terms of a−, b−, c− axis thermal conductivity. Various inadequacies involved due to dispersion and violation of Matthessien’s rule in the Callaway’s model have been removed with the help of life time approach of quantum many body theory of scattering mechanisms. Based on this approach the thermal conductivity of La1.98Sr0.02CuO4 and La1.96Sr0.04CuO4 samples has been numerically estimated and the observed results are found in good agreement with experimental observations.The problem of heat transport anisotropy in layered cuprate high temperature superconductors (HTS) has been investigated in terms of a−, b−, c− axis thermal conductivity. Various inadequacies involved due to dispersion and violation of Matthessien’s rule in the Callaway’s model have been removed with the help of life time approach of quantum many body theory of scattering mechanisms. Based on this approach the thermal conductivity of La1.98Sr0.02CuO4 and La1.96Sr0.04CuO4 samples has been numerically estimated and the observed results are found in good agreement with experimental observations.

Superconducting gap in cuprate high temperature superconductors

The many body quantum dynamical evaluation of double time thermodynamic electron Green’s functions followed by generalized electron density of states (EDOS) is used to study the superconducting gap (SG). The dependence of EDOS on defects, anharmonicity and electron-phonon interactions makes the problem quite complicated and challenging but furnishes the more realistic grounds to study the SG both in conventional and high temperature superconductors (HTS). For simplicity, only electron-phonon interaction has been taken up to evaluate the intricate integral to enumerate the SG for representative cuprate HTS: YBa2Cu3O7-δ and results show 2Δ/kBTc ⋍ 7.2.

Anisotropy in superconducting gap in YBa2Cu3O7-δ

Taking into account the modified form of Born-Mayer-Huggins potential (MBMHP) and many body quantum dynamics based Green’s function theory via a modified Hamiltonian which includes the effects of electrons, phonons, anharmonicities, defects and electron-phonon interactions; the quasiparticle renormalized frequency has been obtained and numerically analyzed for high temperature superconductor (HTS) cuprate YBa2Cu3O7-δ. This evaluation enables one to calculate superconducting gap (SG) in [100] and [010] direction through the dispersion of renormalized mode. A higher SG found in [010] than [100] direction at different doping level establishing its anisotropic nature.