title: Exchange-bias phenomenon: the role of the ferromagnetic spin structure.
abstract: The exchange bias of antiferromagnetic-ferromagnetic (AFM-FM) bilayers is found to be strongly dependent on the ferromagnetic spin configuration. The widely accepted inverse proportionality of the exchange bias field with the ferromagnetic thickness is broken in FM layers thinner than the FM correlation length. Moreover, an anomalous thermal dependence of both exchange bias field and coercivity is also found. A model based on springlike domain walls parallel to the AFM-FM interface quantitatively accounts for the experimental results and, in particular, for the deviation from the inverse proportionality law. These results reveal the active role the ferromagnetic spin structure plays in AFM-FM hybrids which leads to a new paradigm of the exchange bias phenomenon.
authors: Department of Chemical-Physics & BCMaterials, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.|IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
authors: R
authors: R
authors: Morales
authors: Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, USA.
authors: Ali C
authors: AC
authors: Basaran
authors: Unité Mixte de Physique CNRS/Thales, 91767 Palaiseau, France and Université Paris Sud, 91405 Orsay, France.
authors: J E
authors: JE
authors: Villegas
authors: IFIMUP-IN and Departamento Física e Astronomia, Universidade do Porto, 4169-007 Porto, Portugal.
authors: D
authors: D
authors: Navas
authors: Department of Chemical-Physics, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
authors: N
authors: N
authors: Soriano
authors: Department of Chemical-Physics, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
authors: B
authors: B
authors: Mora
authors: Department of Chemical-Physics, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
authors: C
authors: C
authors: Redondo
authors: Departament de Física Fonamental and Institut de Nanociència i Nanotecnologia IN2UB, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain.
authors: X
authors: X
authors: Batlle
authors: Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093, USA.
authors: Ivan K
authors: IK
authors: Schuller