title: Tunable High-Field Magnetization in Strongly Exchange-Coupled Freestanding Co/CoO Core/Shell Coaxial Nanowires.
abstract: The exchange bias properties of Co/CoO coaxial core/shell nanowires were investigated with cooling and applied fields perpendicular to the wire axis. This configuration leads to unexpected exchange-bias effects. First, the magnetization value at high fields is found to depend on the field-cooling conditions. This effect arises from the competition between the magnetic anisotropy and the Zeeman energies for cooling fields perpendicular to the wire axis. This allows imprinting predefined magnetization states to the antiferromagnetic (AFM) shell, as corroborated by micromagnetic simulations. Second, the system exhibits a high-field magnetic irreversibility, leading to open hysteresis loops attributed to the AFM easy axis reorientation during the reversal (effect similar to athermal training). A distinct way to manipulate the high-field magnetization in exchange-biased systems, beyond the archetypical effects, was thus experimentally and theoretically demonstrated.
authors: Department of Materials and Environmental Chemistry, Stockholm University , S-10691 Stockholm, Sweden.
authors: German
authors: G
authors: Salazar-Alvarez
authors: Instituto de Física, Universidade Federal do Rio Grande do Sul , 91501-970 Porto Alegre, RS, Brazil.|Departament de Física, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Spain.
authors: Julian
authors: J
authors: Geshev
authors: Departament de Física, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Spain.
authors: Sebastià
authors: S
authors: Agramunt-Puig
authors: Departament de Física, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Spain.
authors: Carles
authors: C
authors: Navau
authors: Departament de Física, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Spain.
authors: Alvaro
authors: A
authors: Sanchez
authors: Departament de Física, Universitat Autònoma de Barcelona , E-08193 Bellaterra, Spain.|ICREA , Pg. Lluís Companys 23, E-08010 Barcelona, Spain.
authors: Jordi
authors: J
authors: Sort
authors: ICREA , Pg. Lluís Companys 23, E-08010 Barcelona, Spain.|Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, and The Barcelona Institute of Science and Technology, Campus UAB , Bellaterra, E-08193 Barcelona, Spain.
authors: Josep
authors: J
authors: Nogués
keywords: CoO; coaxial nanowires; exchange bias; high-field irreversibility; training effects; uncompensated spins