Temperature dependence of the penetration depth and effective dielectric constant measured by YBa2Cu3O7-delta microstrip ring resonators

YBa2Cu3O7-delta(YBCO) superconducting ring resonators with a YBCO ground pl ane were successfully fabricated using double-side YBCO films deposited on LaAlO3 (LAO) substrates. The temperature dependent London penetration depth , Delta lambda = lambda (T) - lambda (5 K), was systematically studied by v arying the oxygen content of the same resonator structure. For fully oxygen ated case (delta = 0.05), the resonator exhibits a quality factor Q > 10(4) at 16 K, and Delta lambda (T) displays a linear behavior over a wide range of temperatures. With increasing delta (e.g. delta = 0.2, 0.4), although D elta lambda is still linear in temperature, the slope changes with increasi ng oxygen deficiency. The results suggest that, in the underdoped regime, t he inelastic scattering of charged carriers may become increasingly promine nt. From the effective dielectric constant obtained from the ring resonator the dielectric constant of the LAO substrate was estimated to be epsilon ( r) congruent to 25.5 at 5 K and a frequency of about 3.6 GHz. (C) 2001 Else vier Science B.V. All rights reserved.