Penetration depth and its doping dependence in YBa2Cu3O7-delta

Using the quasiparticle spectra in the superconducting state, as determined by the eight-band model for YBa2Cu3O7 (YBCO) and a phenomenological intera ction constant K, we have calculated the magnetic penetration depths lambda (a) and lambda(b), respectively, along a and b axes, as functions of temper ature T, for various levels of oxygen doping. Given that these calculations involve no adjustable parameters the quantitative comparison with the expe rimental data yields satisfactory agreement. Moreover, the theoretical resu lts reproduce the empirical relationship between lambda(T) and doping n, as well as, the so-called Uemura plot of 1/lambda(2)(0) vs T-c. We conclude t hat the low-frequency superconducting electromagnetics of YBCO is governed by a simple BCS-like theory in the context of a realistic description of th e normal-state electronic structure.