title: Observation of an atomic exchange bias effect in DyCo4 film.
abstract: The fundamental important and technologically widely employed exchange bias effect occurs in general in bilayers of magnetic thin films consisting of antiferromagnetic and ferromagnetic layers where the hard magnetization behavior of an antiferromagnetic thin film causes a shift in the magnetization curve of a soft ferromagnetic film. The minimization of the single magnetic grain size to increase the storage density and the subsequent demand for magnetic materials with very high magnetic anisotropy requires a system with high HEB. Here we report an extremely high HEB of 4 Tesla observed in a single amorphous DyCo4 film close to room temperature. The origin of the exchange bias can be associated with the variation of the magnetic behavior from the surface towards the bulk part of the film revealed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism techniques utilizing the bulk sensitive transmission and the surface sensitive total electron yield modes. The competition between the atomic exchange coupling in the single film and the Zeeman interaction lead to an intrinsic exchanged coupled system and the so far highest exchange bias effect HEB = 4 Tesla reported in a single film, which is accommodated by a partial domain wall formation.
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 GIF-sur-YVETTE CEDEX, France.
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.affiliation: Institute for Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Lott
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str.15, 12489 Berlin, Germany.
authors.forename: Florin
authors.initials: F
authors.lastname: Radu
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 GIF-sur-YVETTE CEDEX, France.
authors.forename: Fadi
authors.initials: F
authors.lastname: Choueikani
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 GIF-sur-YVETTE CEDEX, France.
authors.forename: Edwige
authors.initials: E
authors.lastname: Otero
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 GIF-sur-YVETTE CEDEX, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ohresser