We report a method that allows the measurement of the absolute size of the magnetic penetration depth λ(T) of large area YBa2Cu3O7−δ films using the two-coil method where a YBa2Cu3O7−δ film is overlapped with a 1-μm-thick Pb film equivalent in size placed in the gap between the drive and receive coil. The drive coil has fewer counter turns on the top section than the bottom, which is closer to the film, so the film’s edge current would be suppressed and the accuracy that depends on geometry is greatly improved. The transition of the Pb film causes a steplike portion in the mutual inductance M(T) graph and the resultant step height leads to the absolute value of λ.
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Lee et al. (1996) studied this question.