Superconducting gap anisotropy of LuNi2B2C thin films from microwave surface impedance measurements - art. no. 100505

Surface impedance measurements of LuNi2B2C superconducting thin films as a function of temperature have been performed down to 1.5 K and at 20 GHz usi ng a dielectric resonator technique. The magnetic penetration depth closely reproduces the standard BCS result, but with a reduced value of the energy gap at low temperature. These data provide evidence for an anisotropic s-w ave character of the order parameter symmetry in LuNi2B2C. From the evaluat ion of the real part of complex conductivity, we have observed constructive (type II) coherence effects in the electromagnetic absorption below T-c.