Evidence for vortex staircases in the whole angular range due to competing correlated pinning mechanisms

SILHANEK, A.; CIVALE, L.; CANDIA, S.; NIEVA, G.; PASQUINI, G.; LANZA, H.

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

AMER PHYSICAL SOC

Año: 1999 vol. 59 p. 13620 - 13623

0163-1829

We present measurements of the angular dependence of the irreversible magnetization of YBa2Cu3O7 single crystals with columnar defects inclined with respect to the c axis. At high fields a sharp maximum centered at the tracks direction is observed. At low fields we identify a lock-in phase characterized by an angle-independent pinning strength and observe an angular shift of the peak towards the c axis that originates in the misalignment between vortices and applied field in anisotropic materials. The interplay among columnar defects, twins, and intrinsic pinning by the ab planes generates a variety of staircase structures. We show that correlated pinning dominates for all orientations of the applied field. [S0163-1829(99)09417-5].