High-precision penetration-depth measurement of as a function of oxygen content

A mutual-inductance technique has been used for the high accuracy determination of the absolute London penetration depth in (Formula presented) thin films. In order to study the influence of the CuO chains, the oxygen content has been varied in a wide range. At low temperatures the penetration depths obey power laws that depend on the sample but not at all on its oxygen depletion. This finding is best explained in terms of (Formula presented)-wave pairing with impurity scattering located in the Cu(Formula presented) planes.