Sequential assembly of phototunable ferromagnetic ultrathin films with perpendicular magnetic anisotropy.

Getting organized: Assemblies of ferromagnetic FePt nanoparticles were generated with large perpendicular magnetic anisotropy by a magnetic-field-assisted layer-by-layer method, and subsequently layer-by-layer films consisting of L1(0)-FePt nanoparticles and organic polymers were prepared. These films are phototunable when photochromic molecules are used as polymer layers.