The E↵ect of Hydrogen Adsorption on the Magnetic Properties of a Surface Nanocluster of Iron

Pavel F. Bessarab, Valery M. Uzdin, and Hannes Jónsson Science Institute and Faculty of Physical Sciences, VR-III, University of Iceland, Reykjav́ık, Iceland Department of Physics, St. Petersburg State University, St. Petersburg, 198504, Russia National Research University of Information Technologies, Mechanics and Optics, St. Petersburg, 197101, Russia and Dept. of Applied Physics, Aalto University, Espoo, FI-00076, Finland Abstract The e↵ect of hydrogen adsorption on the magnetic properties of an Fe3 cluster immersed in a Cu(111) surface has been calculated using densifty functional theory and the results used to parametrize an Alexander-Anderson model which takes into account the interaction of d-electrons with itinerant electrons. A number of adatom configurations containing one to seven H-atoms were analyzed. The sequential addition of hydrogen atoms is found to monotonically reduce the total magnetic moment of the cluster with the e↵ect being strongest when the H-atoms sit at lowcoordinated sites. Decomposition of the charge density indicates a transfer of 0.3 electrons to each of the H-atoms from both the Fe-atoms and from the copper substrate, irrespective of adsorption site and coverage. The magnetic moment of only the nearest neighbor Fe-atoms is reduced, mainly due to increased population of minority spin d-states. This can be modeled by increased indirect coupling of d-states via the conduction s-band in the Alexander-Anderson model.