title: Single crystalline superstructured stable single domain magnetite nanoparticles.
abstract: Magnetite nanoparticles exhibit magnetic properties that are size and organization dependent and, for applications that rely on their magnetic state, they usually have to be monodisperse. Forming such particles, however, has remained a challenge. Here, we synthesize 40 nm particles of magnetite in the presence of polyarginine and show that they are composed of 10 nm building blocks, yet diffract like single crystals. We use both bulk magnetic measurements and magnetic induction maps recorded from individual particles using off-axis electron holography to show that each 40 nm particle typically contains a single magnetic domain. The magnetic state is therefore determined primarily by the size of the superstructure and not by the sizes of the constituent sub-units. Our results fundamentally demonstrate the structure - property relationship in a magnetic mesoparticle.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Victoria
authors.initials: V
authors.lastname: Reichel
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: András
authors.initials: A
authors.lastname: Kovács
authors.affiliation: Institute of Geophysics, ETH-Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland.
authors.forename: Monika
authors.initials: M
authors.lastname: Kumari
authors.affiliation: Department of Earth and Environmental Sciences, University of Pannonia, Egyetem u. 10, H8200 Veszprém, Hungary.
authors.forename: Éva
authors.initials: É
authors.lastname: Bereczk-Tompa
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Schneck
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Diehle
authors.affiliation: Department of Earth and Environmental Sciences, University of Pannonia, Egyetem u. 10, H8200 Veszprém, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Pósfai
authors.affiliation: Institute of Geophysics, ETH-Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Hirt
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Martial
authors.initials: M
authors.lastname: Duchamp
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany.
authors.forename: Damien
authors.initials: D
authors.lastname: Faivre
mesh_terms: D052203:Ferrosoferric Oxide / Q000737:chemistry; D006696:Holography; D058185:Magnetite Nanoparticles / Q000737:chemistry / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D033363:Neutron Diffraction; D010316:Particle Size; D010455:Peptides / Q000737:chemistry; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D058185:Magnetite Nanoparticles; D010455:Peptides; C015462:polyarginine; D052203:Ferrosoferric Oxide