Energy gap and London penetration depth of MgB_2 films determined by microwave resonator measurement

N. Klein, B. B. Jin, J. Schubert +5

We have measured the temperature dependence of the microwave surface impedance Z_s = R_s + iΩμ_0 of a MgB2 film at a frequency Ω/2Πof 18 GHz employing a dielectric resonator techni…