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

Abstract

YBa2Cu3O7-delta(YBCO) superconducting ring resonators with a YBCO ground plane 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 varying the oxygen content of the same resonator structure. For fully oxygenated 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 Delta lambda is still linear in temperature, the slope changes with increasing oxygen deficiency. The results suggest that, in the underdoped regime, the inelastic scattering of charged carriers may become increasingly prominent. 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 Elsevier Science B.V. All rights reserved.