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Tunneling spectroscopy measurements on low-leakage junctions of Nd1.85Ce0.15CuO4-y and Ba1-xKxBiO3

Conference ·
OSTI ID:6289962
;  [1]; ; ;  [2]
  1. Illinois Inst. of Tech., Chicago, IL (USA)
  2. Argonne National Lab., IL (USA)
+ Show Author Affiliations
Tunneling measurements are reported for Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4{minus}y} (NCCO) and Ba{sub 1{minus}x}K{sub x}BiO{sub 3} (BKBO) using the point-contact technique with a Au or Nb tip. The junctions display very low zero-bias conductance values of <1% for BKBO and {approximately}10% for NCCO, and show sharp conductance peaks at eV = {plus minus} {Delta}. In the case of BKBO, the normalized conductance can be fit with a BCS density of states with thermal smearing only. The energy gaps are in good agreement with optical measurements and lead to values of 2{Delta}k{Tc} in the range of 3.5--4.0 for both compounds implying moderate coupling strength. The tunneling conductance data at high bias voltages display reproducible structures which are characteristic of phonon effects as found in conventional superconductors. We have obtained the Eliashberg functions, {alpha}{sup 2}F({omega}), and the resulting values of {lambda} determined from this analysis are consistent with the measured values of the strong-coupling ratio, 2{Delta}/k{Tc}. We conclude that the pairing mechanism in both materials is principally phonon mediated. 12 refs., 6 figs., 1 tab.
Research Organization:
Argonne National Lab., IL (USA)
Sponsoring Organization:
DOE/ER; NSF
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
6289962
Report Number(s):
CONF-900944-29; ON: DE91006585
Country of Publication:
United States
Language:
English

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Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
426001 -- Engineering-- Superconducting Devices &amp; Circuits-- (1990-)
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
BISMUTH COMPOUNDS
BISMUTH OXIDES
CERIUM COMPOUNDS
CERIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY GAP
HIGH-TC SUPERCONDUCTORS
JUNCTIONS
NEODYMIUM COMPOUNDS
NEODYMIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
POTASSIUM OXIDES
RARE EARTH COMPOUNDS
SPECTROSCOPY
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS