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FIZIKA A 8 (1999) 4 , 267-274
 
SUPPRESSION OF SUPERCONDUCTING FLUCTUATIONS IN THE ELECTRICAL
CONDUCTIVITY IN OXYGEN UNDERDOPED AND OXYGEN OVERDOPED Bi2Sr2CaCu2O8
SINGLE CRYSTALS
LÁSZLÓ FORRÓ
École Polytechnique Fédérale de Lausanne,CH-1015 Lausanne,
Switzerland
Dedicated to Professor Boran Leontić on the occasion of his 70th
birthday
Received 15 November 1999; revised manuscript received 12 April 2000
Accepted 12 April 2000
The ab plane resistivity of the same single crystals of Bi2Sr2CaCu2O8
at different oxygen stoichiometries has been measured. As the oxygen content is lowered,
the crystals become underdoped and the transition temperature (Tc) falls off
from 85 to 58 K. Increasing the oxygen concentration causes the crystals to become
overdoped and the Tc falls off again. The contribution to the electrical
conductivity from superconducting fluctuations above Tc falls off drastically
as oxygen concentration deviates from the optimum. We argue that the data may be
consistent with a relatively large Maki - Thompson contribution, which falls off sharply
both in the underdoped and overdoped regions - probably because of pair breaking.
PACS numb4.25.Fy, 74.40.+K, 74.7ers: 72.Hs
UDC 538.945
Keywords: superconductivity, Bi2Sr2CaCu2O8,
oxygen underdoped and overdoped, transition temperature, Maki - Thompson model, pair
breaking
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