Abstract
We report the first direct experimental evidence of intrinsic pinning in hysteresis loops of untwinned single crystals, for magnetic fields perpendicular to the c axis. We have observed oscillations in the M-H loops that are well explained when one considers the layered structure of this compound. The oscillations are found to be periodic in and are induced by a succession of transitions between states for which the vortex lattice is commensurate with the crystal lattice periodicity in the direction perpendicular to the planes. The following anisotropy parameters were extracted from the experimental results: =(/=6.3, =(/=5.6, and =(/=1.13.
- Received 10 February 1994
DOI:https://doi.org/10.1103/PhysRevLett.72.3606
©1994 American Physical Society