Related papers: BCS theory with the external pair potential
Lately, there has been much interest in high temperature superconductors, and more recently hydrogen-based superconductors. This work offers a simple model which explains the behavior of the superconducting gap based on BCS theory, and…
We study the three-dimensional U(1)+Higgs theory (Ginzburg-Landau model) as an effective theory for finite temperature phase transitions from the 1 K scale of superconductivity to the relativistic scales of scalar electrodynamics. The…
In the context of a simple model featuring an explicit, central interaction potential, and using a standard functional-integral technique, we study superconductivity with angular momentum quantum number l=2 as an emergent property of the…
A grand canonical system of hard-core bosons, subject to thermal fluctuations, is studied on a lattice. Starting from the slave-boson representation with fields for occupied and unoccupied sites, an effective field theory is derived in…
In the main part of this PhD thesis, we consider a periodically realized microscopic superconductor described by BCS theory, which is subject to external electromagnetic fields. We show that the superconductor is properly described by…
The model of hypothetical superconductivity, where the energy gap asymptotically approaches zero as temperature or magnetic field increases, has been proposed. Formally the critical temperature and the second critical field for such a…
We study analytic solutions to the Bardeen-Cooper-Schrieffer (BCS) gap equation for isotropic superconductors with finite-range interaction potentials over the full range of temperatures from absolute zero to the superconducting critical…
We have studied disordering effects on the coefficients of Ginzburg - Landau expansion in powers of superconducting order - parameter in attractive Anderson - Hubbard model within the generalized $DMFT+\Sigma$ approximation. We consider the…
An application of the general equation obtained in Part I to low critical temperature superconductors utilizing an "ad hoc" phononic theory is developed. Then, we arrive to a specific expression for the bounding energy as a function of…
The intimate connection between antiferromagnetism and superconductivity is at the core of high-temperature superconductivity. Here, we put forward the projected BCS theory for the unification of antiferromagnetism at half filling and…
The influence of finite temperatures and pairing correlations on the ground state properties of multi $\Lambda$- Ca, Sn and Pb hypernuclei is explored using finite temperature Hartree Fock Bogoliubov approach and contact pairing…
We prove that in the reduced quartic BCS model with an imaginary external magnetic field a spontaneous U(1)-symmetry breaking (SSB) and an off-diagonal long range order (ODLRO) occur. The system is defined on a hyper-cubic lattice with…
The basic feature of the BCS theory is that pairing occurs between electrons in states with opposite momentum and opposite spins, e.g., between states (k) and (-k), in which the symbols of vectors are neglected, and later theories followed…
We show theoretically that a superconducting critical temperature can be effectively increased in a high-entropy mixture of electrons belonging to conduction and valence bands. In order to employ the entropy of mixing into the…
How the superconductivity in unconventional superconductors emerges from the diverse mother normal states is still a big puzzle. Whatever the mother normal states are the superconductivity is {\em normal} with BCS-like behaviours of the…
The Ginzburg-Landau theory is analyzed in the case of small dimension superconductors, a couple of orders of magnitude above the coherence length, where the theory is still valid but quantum fluctuations become significant. In this regime,…
We study the energy gap within the Dynes superconductor theory. This model generalizes the Bardeen-Cooper-Schrieffer (BCS) approach by including the pair-breaking scattering, introducing the tunneling in-gap states up to a Fermi level. We…
The Cooper pair is generally analyzed in momentum space, but its real-space structure also follows directly from the BCS theory. It is shown here that this leads to a spherically symmetrical quasi-atomic wavefunction, with an identical…
We first argue that the collective behaviour of the Cooper pairs created by thermal fluctuations well above the superconducting transition temperature, Tc, is dominated by the uncertainty principle which, in particular, leads to a…
The usual formulation of the BCS ansatz for superconductivity in the grand canonical ensemble makes the handling of the Pauli exclusion principle between paired electrons straightforward. It however tends to mask that many-body effects…