Minoru Suzuki et al 2009 J. Phys.: Conf. Ser. 150 052252 doi:10.1088/1742-6596/150/5/052252
Minoru Suzuki1,2, Takashi Hamatani1, Yoshiharu Yamada1, Kenkichi Anagawa1 and Takao Watanabe3
Show affiliationsThe Josephson critical current density Jc has been measured for intrinsic Josephson junctions (IJJs) in Bi2Sr2>CaCu2O7+δ using mesas 5 ~10 /μm on a side and 7~15 nm in thickness at various doping levels. The superconducting gap and the normal tunneling resistance are measured at the same time by short-pulse tunneling spectroscopy. It is found that Jc decreases significantly by approximately one order of magnitude when the doping level p is decreased from p = 0.14 for the optimal doping to p = 0.09 in the underdoped region. This significant decrease in Jc, reflecting the bulk properties, can be interpreted in two different ways. If there occurs a phase separation in which superconducting (S) and normal regions (N) coexist on a fine scale, the significant decrease in Jc is explained as a decrease in the S region area. If a decrease in the doping level causes a decrease in the carrier density in the antinodal directions, it is expected that the superconducting pair density decreases due to the d-wave symmetry.
74.25.Fy Transport properties (electric and thermal conductivity, thermoelectric effects, etc.)
74.62.Dh Effects of crystal defects, doping and substitution
74.50.+r Tunneling phenomena; point contacts, weak links, Josephson effects
Issue 5 (2009)
Minoru Suzuki et al 2009 J. Phys.: Conf. Ser. 150 052252
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