We present long-term relaxation measurements of the irreversible magnetization in (Formula presented) single crystals with columnar defects. Within the single vortex pinning regime we find a nonglassy response at intermediate currents, in between the half loops and superkinks glassy regimes. We demonstrate that such behavior is due to double kink excitations whose critical nucleus has a size independent of current, and occur even in the presence of pinning energy dispersion.
|Número de páginas
|Physical Review B - Condensed Matter and Materials Physics
|Publicada - 2000
|Publicado de forma externa