An excess current in Bi2223-Ag contacts above the critical temperature

作者：Dyachenko A I^*; Tarenkov V Yu; Sidorov S L; Varyukhin V N; Soloviev A L

来源：Low Temperature Physics, 2013, 39(4): 323-328.

DOI：10.1063/1.4801989

• BCS theory
• bismuth compounds
• calcium compounds
• Cooper pairs
• lead compounds
• proximity effect (superconductivity)
• strontium compounds
• superconducting energy gap
• superconducting transition temperature

In contacts normal metal-superconductor Bi1.6Pb0.4Sr1.8Ca2.2Cu3O10 (Bi2223), the energy gap Delta(T) of the superconductor and the excess current I-exc(T) were measured by means of the Andreev spectroscopy. It is shown that the parameter Delta(T) turns to zero at the superconducting transition temperature of the cuprate, T-c approximate to 110 K, and the dependence Delta(T) follows the BCS theory; at the same time, the excess current I-exc(T) persists up to the temperature T-pair approximate to 180 K, significantly higher than T-c. The result obtained indicates a possible existence in Bi2223 of a wide temperature range T-c < T < T-pair where a condensate of Cooper pairs starts to form.

• 出版日期2013-4