Microwave properties of a Y0.7Ca0.3Ba2Cu3O7-delta inicrostrip ring resonator with various hole concentrations

Abstract

Superconducting ring resonator with a Y0.7Ca0.3Ba2Cu3O7-delta ground plane was fabricated by using Y0.7Ca0.3Ba2Cu3O7-delta thin film deposited on both sides of a LaAlO3 (LAO) substrate. The resonator exhibits a high quality factor Q > 10(4) at T < 30 K, and from empirical relation,T-c/T-c,T-max = 1 - 82.6(p - 0.16)(2), we obtained the hole concentration p. By controlling the oxygen contents of the ring resonator, the hole concentration p was controlled from 0.218 to 0.088, determined by the empirical relation, in the same film. The temperature dependence of the resonance frequency, f(T), was then systematically studied. By using Chang's inductive formula and taking a functional form (lambda(5K)/lambda (T))(2) = 1 - (T/T-c)(2) at T < 0.6T(c), the London penetration depths lambda(5K) for various oxygen contents at 5K were obtained, respectively. Finally, it allows us to test the Uemura relation 1 /lambda(2)(5K) proportional to T-c from the over- to the underdoped regime in the same sample. (C) 2004 Elsevier B.V. All rights reserved.