We have measured the irreversible magnetization M_i of an ErBa_2Cu_3O_7 single crystal with columnar defects (CD), using a technique based on sample rotation under a fixed magnetic field H. This method is valid for samples whose magnetization vector remains perpendicular to the sample surface over a wide angle range - which is the case for platelets and thin films - and presents several advantages over measurements of M_L(H) loops at fixed angles. The resulting M_i(\Theta) curves for several temperatures show a peak in the CD direction at high fields. At lower fields, a very well defined plateau indicative of the vortex lock-in to the CD develops. The H dependence of the lock-in angle \phi_L follows the H^{-1} theoretical prediction, while the temperature dependence is in agreement with entropic smearing effects corresponding to short range vortex-defects interactions.
@article{arxiv.cond-mat/0107011,
title = {Irreversible magnetization under rotating fields and lock-in effect on ErBa_2Cu_3O_7 single crystal with columnar defects},
author = {M. A. Avila and L. Civale and A. V. Silhanek and R. A. Ribeiro and O. F. de Lima and H. Lanza},
journal= {arXiv preprint arXiv:cond-mat/0107011},
year = {2009}
}
Comments
7 pages, 6 figures, to be published in Phys. Rev. B