Temperature dependence of superfluid YBa2Cu3O7-delta and Y0.7Ca0.3Ba2Cu3O7-delta density in thin films: A doping dependence study of the linear slope

Abstract

By using a microstrip ring resonator to measure the temperature dependence of the in-plane magnetic penetration depth lambda(T) in YBa2Cu3O7-delta (YBCO) and Y0.7Ca0.3Ba2Cu3O7-delta (Ca-YBCO) epitaxially grown thin films, the linear temperature dependence of the superfluid density rho(s)/m* &3bond; I/lambda(2)(T) was observed from the under- to the overdoped regime at the temperatures below T/T-c approximate to 0.3. For the underdoped regime of YBCO and Ca-YBCO thin films, the magnitude of the slope d(1/lambda(2)(T))/dT is insensitive to doping, and it can be treated in the framework of projected d-density-wave model. Combining these slope values with the thermal conductivity measurements, the Fermi-liquid correction factor alpha(2) from the Fermi-liquid model, suggested by Wen and Lee, was revealed here with various doping levels. (c) 2005 Elsevier B.V. All rights reserved.