Bardeen-Cooper-Schrieffer

Some years later a more thorough discussion of the motion of pairs of electrons in a metal was given by Cooper,7 as well as by Abrikosov8 and Gor kov,9 who emphasized that the effective charge in superconductivity is 2e, rather than e. The quantization of flux in units hc/2e in superconducting metals has been verified by direct experimental measurement of the magnetic moments induced in thin films.10 Cooper s discussion of the motion of electron pairs in interaction with phonons led to the development of the Bardeen-Cooper-Schrieffer (BCS) theory, which has introduced great clarification in the field of superconductivity.2... 

The jump in ce is due to the fact that the superconducting metal has a new degree of freedom, i.e. the possibility of entering the superconducting state. For simple superconductors, such as A1 and Sn, the Bardeen-Cooper-Schrieffer (BCS) theory [18-22] gives ... 

Now — L is the Landau-Ginzburg free energy, where m2 = a(T — Tc) near the critical temperature, is a macroscopic many-particle wave function, introduced by Bardeen-Cooper-Schrieffer, according to which an attractive force between electrons is mediated by bosonic electron pairs. At low temperature these fall into the same quantum state (Bose-Einstein condensation), and because of this, a many-particle wave function (f> may be used to describe the macroscopic system. At T > Tc, m2 > 0 and the minimum free energy is at = 0. However, when T [Pg.173]

One of the most amazing phenomena in quantum many-particle systems is the formation of quantum condensates. Of particular interest are strongly coupled fermion systems where bound states arise. In the low-density limit, where even-number fermionic bound states can be considered as bosons, Bose-Einstein condensation is expected to occur at low temperatures. The solution of Eq. (6) with = 2/j, gives the onset of pairing, the solution of Eq. (7) with EinP = 4/i the onset of quartetting in (symmetric) nuclear matter. At present, condensates are investigated in systems where the cross-over from Bardeen-Cooper-Schrieffer (BCS) pairing to Bose-Einstein condensation (BEC) can be observed, see [11,12], In these papers, a two-particle state is treated in an uncorrelated medium. Some attempts have been made to include the interaction between correlated states, see [7,13]. 

Fig. 13. Density of states in the Sn superconductor [38], 1, Experimental curve obtained at 0.3 K 2, the calculation using the Bardeen Cooper-Schrieffer formula (23).

In the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity the transition temperature Tc strongly increases with At(Ep) ... 

Band gap -> semiconductor Band-pass filter -> signal filtering Band-stop filter -> signal filtering Bardeen-Cooper-Schrieffer theory -> BCS theory Barker, Geoffrey Cecil... 

Rosseinsky et al. also suggested a simple reason for the large increase in transition temperature when Rb is substituted for K. The most elementary, widely understood theory of superconductivity, the weak-coupling Bardeen-Cooper-Schrieffer (BCS) model,[Bat57] predicts a simple connection between transition temperature Tc, phonon energy w, electron-phonon coupling strength V, and the density of electron states at the Fermi surface N EfI... 

The superconductivity in the A3(C6o) compounds is of the conventional Bardeen-Cooper-Schrieffer (BCS) type. The relatively high superconducting transition temperature (18 K for A = potassium) is ascribed to electron pair formation mediated by the high energy internal modes [38]. 

Af,AT-bis(2-chloroethyl)-Af-nitrosourea bromocresol purple bromochlorophenol blue Bardeen-Cooper-Schrieffer (theory) bond dissociation energy butyldiethanolamime benzyldimethylamine... 

Bardeen-Cooper-Schrieffer (BCS) theory - A theory of superconductivity which is based upon the formation of electron pairs as a result of an electron-lattice interaction. The theory relates the superconducting transition temperature to the density of states and the Debye temperature. 

Bardeen-Cooper-Schrieffer (D (BCS) Mattis-Bardeen behavior (8) and which, therefore, provides the possibility of an experimental means of identifying the paired holon superconductor. 

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