Место издания:Elsevier Science Publishing Company, Inc
Первая страница:85
Последняя страница:90
Аннотация:A clear gap structure has been observed in the current-voltage characteristics (CVC) of stacks of S-I-S junctions obtained in Bi2Sr2CaCu2O8+d (BSCCO) crystals using a break junction technique. Due to the high resistance of the stacks, the range of bias voltages could be extended well above the gap voltage Vgn without significant overheating of the contacts. For samples with a critical temperature Tc=84-89 K and 2D/kTc=6.7+/-0.3, the value of Vgn corresponding to a steep rise of the quasiparticle current Iqp is well-described by the relation Vgn=n(2D/e) with a gap parameter D(4.2 K)=(25+/-1) meV. The presence of a sharp gap feature in characteristics of stacks points to an essential contribution of s-wave pairing to the symmetry of the order parameter in BSCCO.