%0 Journal Article
%T Evidence for vortex staircases in the whole angular range due to competing correlated pinning mechanisms
%A A. Silhanek
%A L. Civale
%A S. Candia
%A G. Nieva
%A G. Pasquini
%A H. Lanza
%J Physics
%D 1999
%I arXiv
%R 10.1103/PhysRevB.59.13620
%X We analyze the angular dependence of the irreversible magnetization of YBa$_2$Cu$_3$O$_7$ crystals with columnar defects inclined from 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 material anisotropy. The interplay among columnar defects, twins and ab-planes generates a variety of staircase structures. We show that correlated pinning dominates for all field orientations.
%U http://arxiv.org/abs/cond-mat/9902302v1