Vortex-lattice melting in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+[delta]] epitaxial films: Role of the oxygen stoichiometry

Journal Article · Mon Aug 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.3446· OSTI ID:6735527

Balestrino, G; Livanov, D V; Milani, E ^[1]; Camarota, B; Fiorani, D; Testa, A M ^[2]

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1. Dipartimento di Ingegneria Meccanica, Universita di Roma, Tor Vergata, via O. Raimondo 8, I-00173 Roma (Italy)
2. Consiglio Nazionale delle Ricerche, Istituto di Chimica del Materiali, P.O. Box 10, 00016 Monterotondo Stazione (Italy)

We have studied the effects of the oxygen stoichiometry on the magnetic irreversibility line and on the decay of the zero-field-cooled (ZFC) magnetization in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+[delta]] epitaxial films. We have found that the irreversibility line is shifted to lower temperatures and fields (relative to the as-grown sample) by reducing thermal treatments, while it is slightly affected by oxidizing treatments. The decay of the ZFC magnetization is also strongly affected by the oxygen content: although at low temperatures ([ital T]/[ital T][sub [ital c]0][le]0.1) the decay rate of the ZFC magnetization does not depend on the oxygen content, as temperature increases, the relaxation becomes faster with decreasing the oxygen content (above [ital T]/[ital T][sub [ital c]0][similar to]0.3 for the reduced sample the time decay is so rapid that it cannot be measured). Such effects are explained taking into account the strong dependence of the effective anisotropy in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8+[delta]] on the oxygen content. The effective anisotropy is higher in reduced samples, thus shifting the vortex-lattice melting temperature toward lower values. From the analysis of the magnetic irreversibility lines, values of the effective anisotropy factor [gamma] have been obtained for different degrees of oxidation. These results are in good agreement with other estimates obtained by different techniques.

• OSTI ID: 6735527
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:5; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
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STOICHIOMETRY
CALCIUM OXIDES
CUPRATES
HIGH-TC SUPERCONDUCTORS
STRONTIUM OXIDES
ABRIKOSOV THEORY
ANISOTROPY
EPITAXY
MAGNETIZATION
MIXED STATE
SUPERCONDUCTING FILMS
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
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CHALCOGENIDES
COPPER COMPOUNDS
FILMS
OXIDES
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