Comparison of paramagnetic- and nonmagnetic-impurity effects on superconductivity in Nd sub 1. 85 Ce sub 0. 15 CuO sub 4
- Superconductivity Research Laboratory, International Superconductivity Technology Center, 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, Japan (JP)
The effects of substitution of Co, Ni, or Zn for Cu in the electron-doped superconductors, Nd{sub 1.85}Ce{sub 0.15}Cu{sub 1{minus}{ital x}M{ital x}}O{sub 4} (with {ital M}=Co, Ni, or Zn, {ital x}{le}0.05), have been investigated by powder x-ray diffraction analysis and resistivity, magnetic-susceptibility, and Hall-coefficient measurements. It is observed that only 0.7% Co or 0.8% Ni substitution for Cu destroys superconductivity. On the contrary, for the Zn-substituted samples, it is observed that {ital T}{sub {ital c}} decreases proportionally to {ital x} and the magnitude of {ital T}{sub {ital c}} is {similar to}9 K even for the 2% Zn-substituted sample. This result suggests that the pair-breaking effect plays a dominant role in the suppression of superconductivity in the Co- or Ni-substitute samples. The absolute values of the exchange-interaction energy between an electron and a Co ion and of that between an electron and a Ni ion are estimated at {similar to}0.09 and {similar to}0.08 eV, respectively. These values are comparable to those of the conventional BCS-type superconductors containing paramagnetic impurities. Both the absolute value of the Hall coefficient ({vert bar}{ital R}{sub {ital H}}{vert bar}) and its temperature coefficient ({ital d}{vert bar}{ital R}{sub {ital H}}{vert bar}/{ital dT}) are found to decrease as {ital x} increases for all the samples at temperatures higher than 120 K. However, for the Co-substituted samples, it is clearly observed that {vert bar}{ital R}{sub {ital H}}{vert bar} increases proportionally to {ital x} at 30 K, while {vert bar}{ital R}{sub {ital H}}{vert bar} decreases monotonically with increasing {ital x} for the Ni- or Zn-substitute samples. Therefore, it seems that there are no clear relations between the temperature dependence of {ital R}{sub {ital H}} and the suppression in the magnitude of {ital T}{sub {ital c}} due to the substitutional effects.
- OSTI ID:
- 5692206
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Vol. 43:13; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CERIUM OXIDES
SUPERCONDUCTIVITY
COPPER OXIDES
NEODYMIUM OXIDES
COBALT ADDITIONS
EXCHANGE INTERACTIONS
HALL EFFECT
MAGNETIC SUSCEPTIBILITY
NICKEL ADDITIONS
QUANTITY RATIO
TRANSITION TEMPERATURE
X-RAY DIFFRACTION
ZINC ADDITIONS
ALLOYS
CERIUM COMPOUNDS
CHALCOGENIDES
COBALT ALLOYS
COHERENT SCATTERING
COPPER COMPOUNDS
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
INTERACTIONS
MAGNETIC PROPERTIES
NEODYMIUM COMPOUNDS
NICKEL ALLOYS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
ZINC ALLOYS
360204* - Ceramics
Cermets
& Refractories- Physical Properties