Experimental evidence of a crossover in the vortex dimensionality in high-{ital T}{sub {ital c}} superconductors

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.362568· OSTI ID:280108

Garcia, A; Zhang, X X; Tejada, J ^[1]

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1. Departament de Fisica Fonamental, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain)

Quantum motion of vortices in high-temperature superconductors (HTSCs) was studied via magnetic relaxation measurements performed with a commercial superconducting quantum interference device magnetometer. At a fixed temperature, the field dependence of the time-logarithmic magnetic relaxation rate normalized to the first magnetization value, {ital R}={parallel}{ital d}({ital M}/{ital M}{sub 0})/{ital d}ln({ital t}){parallel}, was investigated in different polycrystalline HTSCs: TlBaCaCuO (2212 and 2223 single phases), YBaCuO (123 phase), and (Hg,Tl)BaCaCuO (1223 phase). The results obtained for TlBaCaCuO 2223 phase and (Hg,Tl)BaCaCuO show a common trend: {ital R} increases linearly with magnetic field up to a certain value, the dimensional crossover field {ital H}{sub 3D-2D}, above which it becomes field-independent. {ital H}{sub 3D-2D} is a characteristic field which depends on the anisotropy parameter and the interlayer spacing of the material. The field dependence of {ital R} can be ascribed to a crossover in the dimensionality of the object involved in the quantum process: above {ital H}{sub 3D-2D}, the longitudinal dimension of the tunneling object, {ital L}{sub {ital c}}, is smaller than the interlayer distance, so the object is of two-dimensional (2D) nature (2D pancake vortices). Below {ital H}{sub 3D-2D}, 2D vortices in neighboring layers become coupled, so the tunneling object becomes three-dimensional (3D) in nature (3D flux-lines). The field dependences of {ital R} obtained for TlBaCaCuO 2212 phase and YBaCuO show only the 2D and 3D vortex regimes, respectively. Well agreement between theoretical estimates and experimental values for the dimensional crossover field and normalized relaxation rates is achieved. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 280108
• Report Number(s): CONF-951101--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 79; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
COPPER OXIDES
CRITICAL CURRENT
HIGH-TC SUPERCONDUCTORS
MAGNETIC FIELDS
MULTILAYERS
SILICON OXIDES
SUPERCONDUCTING FILMS
TEMPERATURE DEPENDENCE
YTTRIUM OXIDES
ZIRCONIUM OXIDES