ac susceptibility in YBa[sub 2](Cu[sub 1[minus][ital x]]Fe[sub [ital x]])[sub 3]O[sub 7[minus][delta]]: Evidence for two-step irreversibility-line crossover

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.483· OSTI ID:5529012

Mehbod, M ^[1]; Sergeenkov, S; Ausloos, M ^[2]; Schroeder, J ^[1]; Dang, A ^[3]

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1. Service de Physique des Solides, Universite Libre de Bruxelles, CP 233, boulevard du Triomphe, B-1050 Brussels (Belgium)
2. S.U.P.RS., B5, Institute of Physics, University of Liege, Sart Tilman, B-4000 Liege (Belgium)
3. S.U.P.RS., B5, Institute of Physics, University of Liege, Sart Tilman, B-4000 Liege (Belgium) Service de Physique des Solides, Universite Libre de Bruxelles, CP 233, boulevard du Triomphe, B-1050 Brussels (Belgium)

The ac susceptibilities of YBa[sub 2](Cu[sub 1[minus][ital x]]Fe[sub [ital x]])[sub 3]O[sub 7[minus][delta]] polycrystals for 0[le][ital x][lt]0.05 have been measured as a function of temperature and magnetic-field strength. Two different types of behavior of the irreversibility line, [ital T][sub [ital m]]([ital H]), obeying the law 1[minus][ital T][sub [ital m]]/[ital T][sub [ital c]][similar to][ital H][sup [ital q]] have been found. One corresponds to pure Y-Ba-Cu-O ([ital x]=0) and shows the commonly observed change of the power exponent [ital q] from 2/3 to 1 with increasing field. For the iron-doped samples an additional unusual crossover from [ital q]=1 to [ital q]=4/3 is observed practically within the same field and temperature interval as for the undoped one. The obtained results are described via the critical-state model taking into account the modification of the Josephson medium for the iron-doped case. In contrast to the silver-doped case [S.L. Shinde [ital et] [ital al]., Phys. Rev. B 41, 8838 (1990)], the pinning-force densities turn out to be smaller for iron-doped Y-Ba-Cu-O as compared to the undoped sample, probably due to iron-induced creation of a weak-link network inside grains.

• OSTI ID: 5529012
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:1; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
GRAIN BOUNDARIES
HIGH-TC SUPERCONDUCTORS
IRON ADDITIONS
IRON ALLOYS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUBSTOICHIOMETRY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES