| Autor: |
Bondarenko, A. V., Revyakina, M. G., Prodan, A. A., Obolenskií, M. A., Vovk, R. V., Arouri, T. R. |
| Předmět: |
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| Zdroj: |
Low Temperature Physics; Mar2001, Vol. 27 Issue 3, p201, 15p |
| Abstrakt: |
Vortex creep in a single crystal containing unidirectional twin boundaries (TBs) is investigated at temperatures of 82-87 K in a special experimental geometry: J|ab, J|TB, H⊥J, with α≡/_ H,ab as a variable parameter. It is shown that in low magnetic fields the TBs alter the configuration of the structure of the flux lines at angles of misorientation θ between the magnetic field vector H and the planes of the TBs of up to 70°: at angles θ<70° a part of the flux line is trapped by the planes of the TBs. It is shown that a TB is an efficient pinning center for the motion of the vortices perpendicular to the plane of the TB, and therefore in low magnetic fields at angles θ<70° a directed motion of the vortices along the planes of the TBs occurs. The angle dependence of the activation energy for a plastic mechanism of flux creep is determined, and it is found to agree with the theoretical estimates made. For an orientation of the vector H close to the ab plane of the crystal, the maximum of the angle dependence of the measured "critical" current J[sub cE](α) observed for the the H|ab orientation of the field vector in low magnetic fields gives way to a minimum at higher magnetic fields; this is explained by a change from single-vortex creep to collective creep as the magnetic field is increased. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
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