We have studied the phase diagram of MgB2 superconductor using a single crystal for H∥c-axis. For the first time we report the existence of peak effect in the screening current in MgB2 single crystal for H∥c-axis. In the magnetic field regime 10<H<13.5 kOe the local fundamental diamagnetic moment displays a very narrow diamagnetic step, with a temperature width of the same size as the zero dc-magnetic field transition. For higher field this step is transformed to a peak which is related with the peak effect in the screening current. Finally, for H<10 kOe the diamagnetic step is transformed to a gradual transition. Our findings for the vortex matter phase diagram for the MgB2 are closely related with theoretical predictions concerning the vortex matter phase diagram of a type II superconductor in the presence of weak point disorder.
@article{arxiv.cond-mat/0205561,
title = {Peak effect in single crystal MgB$_2$ superconductor for ${\bf H}\parallel c$-axis},
author = {M. Pissas and S. Lee and A. Yamamoto and S. Tajima},
journal= {arXiv preprint arXiv:cond-mat/0205561},
year = {2009}
}
Comments
Has been submitted for publication in PRL since 21 February 2002