|
ИСТИНА |
Войти в систему Регистрация |
ИПМех РАН |
||
ANISOTROPY IN THE IRREVERSIBLE BEHAVIOR OF POINTLIKE DEFECTS AND TWINS IN YBa2Cu3O7-δ SINGLE CRYSTALS WITH A PEAK EFFECTстатья
Информация о цитировании статьи получена из
Scopus,
Web of Science
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Küpfer H., Will A., Jahn W., Meier-Hirmer R., Wolf Th, Zhukov A.A., Voronkova V.I., Kläser M., Saito K.
- Журнал: Physical Review B
- Том: 54
- Номер: 1
- Год издания: 1996
- Издательство: American Physical Society
- Местоположение издательства: United States
- Первая страница: 644
- Последняя страница: 655
- DOI: 10.1103/PhysRevB.54.644
- Аннотация: In different RBa2Cu3O7-δ (R=Y,Tm) single crystals the peak of the current density j vs magnetic field B is investigated in the angular region B parallel and perpendicular to the c axis of the crystals. The magnetic moment from the current is measured as a function of angle φ between field direction and c axis with a vibrating sample magnetometer up to B=7 T. The peak effect which probably results from an isotropic pointlike defect structure (oxygen vacancies, impurities from doping or crucible) is observed in B∥c for the current parallel to the a,b plane (j∥a,b) and in B∥a,b for both currents j∥a,b and j∥c. This was verified in twinned and twin-free crystals. For B∥c the influence of the twin structure on the j(B) peak results in an increase of j below and above the peak from pinning at twin walls. However, in the peak region the current becomes depressed either from channeling of vortices along twin walls or from enhanced stiffness of the tilt modulus of the flux lattice. The twinned crystals show a cusplike dependence of the irreversibility field Birr vs φ with the maximum at B∥c in agreement with a Bose-glass transition. Whereas the detwinned crystal reveals a minimum of Birr(φ) at B∥c as expected from an anisotropic but homogeneous crystal. This interference between pointlike and correlated disorder in the flux lattice becomes less pronounced with larger impurity contents. In B∥a,b intrinsic pinning from CuO layers is observed by an increase of the magnetic moment vs φ. This is further proved by lock-in oscillations which demonstrate the matching condition between crystal layer and flux lattice spacing. At higher fields the moment vs φ shows an unusual decrease in an angular region ±0.3° from B∥a,b. This behavior is related to j∥c which is expected to decrease from shear instability of the flux lattice. © 1996 The American Physical Society.
- Добавил в систему: Воронкова Валентина Ивановна