We present the resistively-determined upper critical field H^{\rho}_{c2}(T) and the irreversibility lines H^{\rho}_{irr}(T) of various high-T_c cuprates, deduced from measurements in 61-T pulsed magnetic fields applied parallel to the c-axis. The SHAPE of both H^{\rho}_{c2}(T) and H^{\rho}_{irr}(T) depends monotonically on the anisotropy of the material and none of the samples show saturation of H^{\rho}(T) at low temperatures. The anomalous positive curvature, d^2 H^{\rho}/dT^2 > 0, is the strongest in materials with the largest normal-state anisotropy, regardless of whether anisotropy is varied by changing the carrier concentration or by comparing a variety of optimally-doped compounds.
@article{arxiv.cond-mat/9908190,
title = {Resistive upper critical fields and irreversibility lines of optimally-doped high-T_c cuprates},
author = {Yoichi Ando and G. S. Boebinger and A. Passner and L. F. Schneemeyer and T. Kimura and M. Okuya and S. Watauchi and J. Shimoyama and K. Kishio and K. Tamasaku and N. Ichikawa and S. Uchida},
journal= {arXiv preprint arXiv:cond-mat/9908190},
year = {2009}
}
Comments
6 pages, 4 figures, accepted for publication in Phys. Rev. B