ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Upper critical magnetic fields Hc2(T) have been measured resistively for the high-temperature (Tc(approximately-greater-than)90 K) superconductors TmBa2Cu3O9−δ and YBa2Cu3O9−δ in applied magnetic fields H up to 9 T. If H at the resistive midpoint is defined as Hc2, then the upper critical field slopes (dHc2/dT)Tc at the superconducting transition temperatures Tc are respectively −2.8 and −1.1 T/K. The Tm-specimen initial slope is apparently the highest yet reported for 90 K superconductors. Extrapolations from this slope, based on standard, three-dimensional, dirty-limit Werthamer, Helfand, Hohenberg, and Maki theory, yield (1) zero-temperature upper critical fields Hc2(T=0)=99–175 T, where the range is determined by the degree of paramagnetic limitation; (2) Hc2(T=77 K)≈36 T, the upper critical field at the boiling point of liquid nitrogen.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.98445
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