FIRST OBSERVATION OF A FULLY MAGNETIC 4D IMPURITY ON THE SURFACE OF AU

We observe for the first time a fully magnetic 4d surface impurity on the surface of a noble metal. Au films are covered with 1/100 of a mon olayer of Mo. The Mo atoms cause a dephasing of the conduction electro n coherence which is of the same order of magnitude as the dephasing b y magnetic Fe atoms. The dephasing is measured by weak localization an d proves the strong magnetic character of the Mo atoms. The magnetic c haracter of Mo is investigated up to a coverage of one monolayer. The dephasing per Mo atom strongly diminishes with increasing Mo coverage.