LOW-TEMPERATURE MEASUREMENTS OF THE MAGNETIC PENETRATION DEPTH IN ELECTRON-DOPED AND HOLE-DOPED SUPERCONDUCTING THIN-FILMS

High sensitivity microwave measurements of the in-plane magnetic penetration depth in c-axis oriented YBa2Cu3O7-delta (YBCO) and Nd1.85Ce0.15CuO4-delta (NCCO) thin films are reported. In the low temperature region, for the NCCO samples lambda(T) follows the expected exponential behavior, while for the YBCO compound the data show a clear quadratic temperature dependence.