A method is presented to measure the absolute value of the London penetration depth, λ(T = O), from the frequency shift of a resonator. The technique involves coating a high-Tc superconductor with film of low-Tc material of known thickness and penetration depth. The method is applied to obtain λ(YBa2Cu3O7 -δ) ≈ 1460 ± 150 Å, λ(Bi2Sr2CaCu2O8 + δ) ≈ 2690 ± 150 Å and λ(Pr1.85Ce0.15CuO4 - δ) ≈ 2790 ± 150 Å. λ(YBa2Cu3O7 - δ) from this method is very close to that obtained by several other techniques. For both Bi2Sr2CaCu2O8 + δ and Pr1.85Ce0.15CuO4 - δ the values exceed those obtained by other methods.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)