INTER-PLANE ELECTROMAGNETIC RESPONSE OF A-AXIS ORIENTED YBCO FILMS INTHE MILLIMETER-WAVE REGION

The temperature dependence of the inter-plane complex conductivity sig ma(1c) - i sigma(2c) of a-axis oriented YBa2Cu3O7-delta thin films dep osited on LaSrGaO4(100) substrates has been measured in the millimeter -wave region by using a Mach-Zehnder type interferometric spectrometer . The value of sigma(1c)(T) increases just below T-c with decreasing t emperature as well as the in-plane conductivity sigma(1ab)(T). The inc rease of sigma(1c)(T) below T-c is due to the strong suppression of th e quasi-particle damping, The value of sigma(2c)(T) increases almost l inearly with decreasing temperature. The temperature dependence of the magnetic penetration depth lambda(c) is deduced from the measured com plex conductivity. it is found that lambda(c)(-2)(T) changes almost li nearly with temperature. The linear behavior of lambda(c)(-2)(T) is co nsistent with the theory in which d-wave superconducting layers are co upled through normal layers.