Penetration Depth Measurements of YBa2Cu3O7-δ at 4 MHz

Abstract

ABSTRACTMeasurements were made of the penetration depth of bulk and powder samples of YBa2Cu3O7-δ. The samples were placed in an inductor which was part of the resonant circuit of a 4 MHz tunnel diode oscillator. The oscillator was stable to at least 1 part in 106 at 77 K. Changes in the sample susceptibility were easily detected by changes in the oscillator frequency. Analysis of the smallest powders fabricated gave a value of the measured penetration depth λmea = 0.23 μm. The measurement methodology is quantitative and the value of Xmea is believed to be an upper bound of the true penetration depth.