Related papers: Cooper-pair size and binding energy for unconventi…
We investigate Bardeen-Cooper-Schrieffer (BCS)- Bose-Einstein condensation (BEC) crossover in a two-band superfluid Fermi gas with an energy shift between the bands. When the intraband coupling in the cold (first) band is fixed as weak, we…
The Cooper-pair size (i.e., the BCS coherence length) in low-dimensional superconductors is dramatically modified by quantum-size effects. In particular, for nanowires made of conventional superconducting materials, we show that the…
We discuss the concept of Cooper pair in the context of recent experimental studies of radio-frequency excitations in ultracold atomic gases. We argue that the threshold energy determines the size of the Cooper pair emergent from the exact…
Cooper pairing in two dimensions is analyzed with a set of renormalized equations to determine its binding energy for any fermion number density and all coupling assuming a generic pairwise residual interfermion interaction. \ Also…
Cooper's original one pair problem in continuum is revisited here corresponding to a lattice of tight binding nature, with an aim to investigate superconductivity in low dimensional systems. An electronic type of boson mediated attraction…
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…
Fermionic superfluidity requires the formation of pairs. The actual size of these fermion pairs varies by orders of magnitude from the femtometer scale in neutron stars and nuclei to the micrometer range in conventional superconductors.…
We analyze conditions of applicability of grand-canonical mean-field Bardeen-Cooper-Schrieffer theory to the evaluation of an interaction energy in the ground state of small-sized superconductors. We argue that this theory fails to describe…
The mutual interaction between Cooper pairs is proposed as a mechanism for the superconducting state. Above $T_c$, pre-existing but fluctuating Cooper pairs give rise to the unconventional {\it pseudogap} (PG) state, well-characterized by…
In part I of this paper a modified BCS mechanism of Cooper pair formation of electrons was proposed. This mechanism is connected with the existence of a narrow, roughly half-filled "superconducting energy band" of given symmetry. The…
The two-flavor color superconductivity is examined over a wide range of baryon density with a single model. To study the structural change of Cooper pairs, quark correlation in the color superconductor is calculated both in the momentum…
Motivated by the recent experiment of the non-BCS scaling relation of the condensation energy $\Delta CE$ vs. $T_c$ ($\Delta CE \sim T_c ^{\beta}, \beta\approx 3.5$) [PRB 89 140503 (2014)] for the Fe-based superconductors, we studied the CE…
The BCS-to-BEC crossover, as well as the nature of Cooper pairs, in a superconducting and Fermi superfluid medium is studied from the exact ground state wavefunction of the reduced BCS Hamiltonian. As the strength of the interaction…
By solution of the Bethe-Goldstone equation for the Cooper pairing problem, an approximate analytic relation is derived between coherence length xi and the binding energy of the Cooper pair. This relation is then qualitatively confirmed by…
Cooper pairing is studied in three dimensions to determine its binding energy for all coupling using a general separable interfermion interaction. Also considered are Cooper pairs (CPs) with nonzero center-of-mass momentum (CMM). A…
We discuss a possibility of transition from color superconductivity of the standard BCS type at high density, to Bose-Einstein Condensation (BEC) of Cooper pairs at lower density. Examining two-flavor QCD over a wide range of baryon…
Understanding the nature of Cooper pairs is essential to describe the properties of superconductors. The original proposal of Bardeen, Cooper, and Schrieffer (BCS) was based on electrons pairing with same energy and zero center-of-mass…
In Part I of this paper a modified BCS mechanism of Cooper pair formation was proposed. The present Part III gives a physical interpretation of this mechanism in terms of spin-flipping processes in superconducting bands.
The Hamiltonian and trial function in the BCS theory are improved to test the limit of this theory. The Cooper pairs arise from standing electron waves, ready to move with atoms, giving high Tc. The Hamiltonian is derived from alternating…
The Cooper pair binding energy {\it vs.} center-of-mass-momentum dispersion relation for Bose-Einstein condensation studies of superconductivity is found in two dimensions for a renormalized attractive delta interaction. It crosses over…