ISSN:
0392-6737
Keywords:
Magnetization curves, Meissner effect, penetration depth
;
Insulator-superconductor transitions
;
unconventional mechanisms of high-T c superconductivity
;
Superconducting films
;
Conference proceedings
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Summary Accurate measurements of the magnetic penetration depth λ ofn-doped (Nd1.85Ce0.15CuO4−δ) andp-doped (YBa2Cu3O7−δ) high-temperature superconductors using a microscopic resonator are reported. The temperature dependence λ(T) in Nd1.85Ce0.15CuO4−δ films shows that the electrodynamics of this cuprate is well described in the framework of the BCS theory, with a single-valued finite-gap ratio 2Δ 0/K B T c≈3.1 throughout the entire temperature range belowT c. In contrast, measurements of λ(T) in YBa2Cu3O7−δ cannot be fitted to a BCS temperature dependence derived from a single energy gap. In the low-temperature region, a quadratic behaviour of the penetration depth is observed, instead of the usual exponential law. These peculiar features are discussed in the light of recent theoretical models predicting a different symmetry state for the high-T c superconductors.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02462193
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