Collective motion of Josephson vortices in intrinsic Josephson junctions in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y}
- Physikalisches Institut III, Universitaet Erlangen-Nuernberg, D-91058 Erlangen (Germany)
- Commonwealth Scientific and Industrial Research Organization, Division of Applied Physics, Lindfield 2070 (Australia)
We report on the experimental observation of moving Josephson vortices in mesa structures patterned on the surface of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+y} single crystals. Mesas form stacks of typically 100 intrinsic Josephson junctions. In magnetic fields parallel to the superconducting copper oxide layers, a flux-flow branch develops on the current-voltage (I-V) characteristic. We investigate this branch in magnetic fields H up to 15 kOe for junctions with lateral dimensions ranging from 20{times}20{mu}m{sup 2} to 500{times}20{mu}m{sup 2}. Investigations show that the voltage of the branch scales with 1/H. For mesas of the same height its slope is inversely proportional to the junction area showing that the flux-flow resistance is independent of the particular junction length. Microwave emission is sensitive to the direction of fluxon motion. This shows that the flux-flow branch in the I-V characteristic is caused by the collective motion of vortices. We compare our data to numerical simulations based on the coupled sine-Gordon equations for strongly coupled, stacked Josephson junctions. We show that the observed branch can be understood as a flux-flow state caused by vortices moving with the lowest collective-mode velocity of the system. The value derived for the Swihart velocity is in good agreement with recent measurements of the c-axis Josephson plasma frequency. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 575887
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 21 Vol. 55; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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