The upper critical fields Bc2(T) were measured up to 28 T for R1Ba2Cu3O7-y, where R=Nd,Eu,Gd,Dy,Ho,Er,andTm, and for YBa2Cu3O7-y. The midpoints (dBc2dT)T=Tc cluster about (2.8"0.2) T/K, the Tc's=(93"2) K show a slight systematic decrease from Nd to Tm, and the extrapolated values of Bc2(0) cluster about (160"20) T. The wide range of normal-state resistivities indicates that they are not intrinsic to the superconductor. The anisotropy A=Bc2 Bc2 is estimated to be less than 12 based on the data for the resistive transition. Criteria for the midpoint resistive transition are also reexamined.
ASJC Scopus subject areas
- Condensed Matter Physics