title: Magnetic remanence in single atoms.
abstract: A permanent magnet retains a substantial fraction of its saturation magnetization in the absence of an external magnetic field. Realizing magnetic remanence in a single atom allows for storing and processing information in the smallest unit of matter. We show that individual holmium (Ho) atoms adsorbed on ultrathin MgO(100) layers on Ag(100) exhibit magnetic remanence up to a temperature of 30 kelvin and a relaxation time of 1500 seconds at 10 kelvin. This extraordinary stability is achieved by the realization of a symmetry-protected magnetic ground state and by decoupling the Ho spin from the underlying metal by a tunnel barrier.
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Donati
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Rusponi
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 Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Wäckerlin
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Singha
authors.affiliation: Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Persichetti
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Baltic
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Diller
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Patthey
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Fernandes
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland. Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Dreiser
authors.affiliation: Vinča Institute of Nuclear Sciences (020), Post Office Box 522, 11001 Belgrade, Serbia. Texas A&M University at Qatar, Doha, Qatar.
authors.forename: Ž
authors.initials: Ž
authors.lastname: Šljivančanin
authors.affiliation: European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble, France.
authors.forename: K
authors.initials: K
authors.lastname: Kummer
authors.affiliation: Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Nistor
authors.affiliation: Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland. pietro.gambardella@mat.ethz.ch harald.brune@epfl.ch.
authors.forename: P
authors.initials: P
authors.lastname: Gambardella
authors.affiliation: Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland. pietro.gambardella@mat.ethz.ch harald.brune@epfl.ch.
authors.forename: H
authors.initials: H
authors.lastname: Brune