High temperature superconducting films on flexible substrates for cryoelectronics

High temperature superconducting (HTS) films on flexible, low loss, low the rmal conductivity substrates offer unique advantages to transmit multichann el digital data with low signal attenuation for cryoelectronic applications . Polycrystalline, flexible yttria stabilized zirconia (YSZ) with a low the rmal conductivity of 0.015 W/cm. K, a low RF loss of 4 x 10(-4) (at 77 K, 5 GHz) and a relatively low dielectric constant of 28 is an excellent choice as a substrate if high quality HTS films can be developed with desirable R IF properties. This paper presents recent data obtained on biaxially textur ed Y1B2C3O7-x (YBCO) films deposited on polycrystalline YSZ substrates with a biaxially-textured YSZ template. YSZ structural templates were developed by Ion beam-assisted pulsed laser deposition (PLD). YBCO films were deposi ted by PLD. The biaxially textured YBCO films exhibit in-plane (Phi-scans) FWHMs of similar to7 degrees. The transition temperatures (T-c's) of the fi lms are in the range 88-89 K with transition widths of 0.5 K. The critical current densities (J(c)'s) measured at 77 K, zero field, are in the range o f 2 x 10(6) A/cm(2). The surface resistance of the films measured at 77 K, 10 GHz is 700 mu Omega indicating a low microwave loss in these films. The high materials quality obtained in these HTS films on polycrystalline subst rates can be used in fabricating a variety of components for cryoelectronic applications. (C) 2001 Elsevier Science B.V. All rights reserved.