title: Reversible photoswitching of ferromagnetic FePt nanoparticles at room temperature.
abstract: There has been a great interest in developing photoswitchable magnetic materials because of their possible applications for future high-density information storage media. In fact, however, the examples reported so far did not show ferromagnetic behavior at room temperature. From the viewpoint of their practical application to magnetic recording systems, the ability to fix their magnetic moments such that they still exhibit room-temperature ferromagnetism is an absolute requirement. Here, we have designed reversible photoswitchable ferromagnetic FePt nanoparticles whose surfaces were coated with azobenzene-derivatized ligands. On the surfaces of core particles, reversible photoisomerization of azobenzene in the solid state was realized by using spacer ligands that provide sufficient free volume. These photoisomerizations brought about changes in the electrostatic field around the core-FePt nanoparticles. As a result, we have succeeded in controlling the magnetic properties of these ferromagnetic composite nanoparticles by alternating the photoillumination in the solid state at room temperature.
authors.affiliation: Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Suda
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakagawa
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Iyoda
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Einaga