INVESTIGADORES
BEKERIS Victoria Isabel
artículos
Título:
Peak effect in YBCO crystals: Statics and dynamics of the vortex lattice
Autor/es:
G. PASQUINI Y V. BEKERIS
Revista:
SUPERCONDUCTOR SCIENCE AND TECHNOLOGY
Editorial:
Elsevier
Referencias:
Año: 2006 vol. 19 p. 671 - 678
ISSN:
0953-2048
Resumen:
Oscillatory dynamics and quasi-static Campbell regime of the vortex lattice
(VL) in twinned YBaâCuâOâ single crystals has been explored at low fields
near the peak effect (PE) region by linear and non-linear ac susceptibility
measurements. We show evidence that the PE is a dynamic anomaly observed in
the non-linear response, and is absent in the Labusch constant derived from
the linear Campbell regime. Static properties play a major role however, and
we identify two H(T) lines defining the onset and the end of the effect. At
Hâ?(T) a sudden increase in the curvature of the pinning potential wells with
field coincides with the PE onset. At a higher field, Hâ(T), a sudden
increase in linear ac losses, where dissipative forces overcome pinning
forces, marks the end of Campbell regime and, simultaneously, the end of the
PE anomaly. Vortex dynamics was probed in frequency dependent measurements,
and we find that in the PE region, vortex dynamics goes beyond the
description of a power law with a finite creep exponent for the constitutive
relation.