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 monolayer of Mo. The Mo atoms cause a dephasing of the conduction electron coherence which is of the same order of magnitude as the dephasing by magnetic Fe atoms. The dephasing is measured by weak localization and proves the strong magnetic character of the Mo atoms. The magnetic character of Mo is investigated up to a coverage of one monolayer. The dephasing per Mo atom strongly diminishes with increasing Mo coverage.