Directional vortex-flux bifurcation in polycrystalline YBa sub 2 Cu sub 3 O sub 7 rotated in a magnetic field

Journal Article · Mon Apr 01 04:00:00 EST 1991 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.43.7859· OSTI ID:5490880

Liu, L; Kouvel, J S ^[1]; Brun, T O ^[2]

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1. Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60680 (USA)
2. P-LANSCE, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)

Magnetization-vector measurements on a field-cooled polycrystalline sample of YBa{sub 2}Cu{sub 3}O{sub 7} rotated in a magnetic field {bold H} at 4.2 K reveal an extraordinary behavior of {bold M}{sub {ital P}}, the penetrating (vortex-flux) component of the magnetization. Near {ital H}=0.8 kOe, as {theta} the sample-rotation angle relative to {bold H} is raised from zero to 360{degree}, the magnitude of {bold M}{sub {ital P}} descends to a small minimum at {theta}{approx}205{degree}, and then again at {theta}{approx}155{degree}, as {theta} is lowered back to 0{degree}. At each minimum, the direction of {bold M}{sub {ital P}} changes very rapidly. For {ital H} at a critical value, the minimum {bold M}{sub {ital P}} reaches zero and its direction changes abruptly by 180{degree}. This behavior signifies a separation of the vortex lines into two groups, one of which rotates rigidly with the sample, while the other maintains a range of orientations extending from that of {bold H} and thus rotates frictionally relative to the sample. The proportion of vortex lines in each group varies systematically with {ital H}. This directional vortex-flux bifurcation can readily arise from a broad distribution in the strength of the vortex-pinning forces. Simple model calculations based on this premise give excellent qualitative agreement with experiment.

• OSTI ID: 5490880
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 43:10; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTALS
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETIZATION
OXIDES
OXYGEN COMPOUNDS
POLYCRYSTALS
TRANSITION ELEMENT COMPOUNDS
ULTRALOW TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES