title: Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.
abstract: We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3  meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.|Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Baumann
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Donati
authors.affiliation: Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Stepanow
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Rusponi
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: W
authors.initials: W
authors.lastname: Paul
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.|Department of Physics, University of California, Davis, California 95616, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gangopadhyay
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: I G
authors.initials: IG
authors.lastname: Rau
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: G E
authors.initials: GE
authors.lastname: Pacchioni
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Gragnaniello
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Pivetta
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.|Swiss Light Source (SLS), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Dreiser
authors.affiliation: Swiss Light Source (SLS), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Piamonteze
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: Lutz
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Macfarlane
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Jones
authors.affiliation: Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Gambardella
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Heinrich
authors.affiliation: Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Brune