BCS TO BOSE CROSSOVER - BROKEN-SYMMETRY STATE

Citation
Jr. Engelbrecht et al., BCS TO BOSE CROSSOVER - BROKEN-SYMMETRY STATE, Physical review. B, Condensed matter, 55(22), 1997, pp. 15153-15156
Citations number
18
Categorie Soggetti
Physics, Condensed Matter
ISSN journal
01631829
Volume
55
Issue
22
Year of publication
1997
Pages
15153 - 15156
Database
ISI
SICI code
0163-1829(1997)55:22<15153:BTBC-B>2.0.ZU;2-#
Abstract
A functional integral formulation, used previously to calculate T-c an d describe normal state proper-ties of the BCS-Bose crossover, is exte nded to T < T-c. The saddle point approximation is shown to be qualita tively correct for T much less than T-c for all couplings, in contrast to the situation above T-c. Several features of the crossover an desc ribed. The difference between the T = 0 ''pair size'' and the (prefact or of the T dependent) Ginzburg-Landau coherence length is pointed out : the two quantities are the same only in the BCS limit. The evolution of the collective modes from the BCS to the Bose regime is discussed together with the mixing of the amplitude and phase in the absence of a particle-hole symmetry.