Measured temperature dependence of the intermodulation product of coplanar waveguides with s- and d-wave superconductors

The measured intermodulation product is compared with the calculation that follows t he interpretation of the BCS-theory according to Dahm and Scalapino in postulating a specific current density and temperature dependence of the London penetration depth: lambda (T,j) approximate to lambda (LT)(T = 0) [[1 - (T/T-c)(4)][1 - b(circle minus)(T)(j/j(c0))(2)]](-0.5) where j(c0) is the current density at zero temperature and b(circle minus)(T) the nonlinearity factor. A good agreement between calculated and measured Values b(circle minus)(T) is obtained if the theoretical d-wave temperature dependence is assumed for YBCO and s-wave behavior for niobium. (C) 2001 Elsevier Science B.V. All rights reserved.