Magnetic anisotropies in ultrathin bismuth iron garnet films

Elena Popova (1) , Andres Felipe Franco Galeano , Marwan Deb , Bénédicte Warot-Fonrose (2) , Hamid Kachkachi , François Gendron (3) , Frédéric Ott (4) , Bruno Berini (1) , Niels Keller (1)

1 GEMAC - Groupe d'Etude de la Matière Condensée
2 CEMES - Centre d'élaboration de matériaux et d'études structurales
3 INSP - Institut des Nanosciences de Paris
4 LLB - UMR 12 - Laboratoire Léon Brillouin

Ultrathin bismuth iron garnet Bi3Fe5O12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi3Fe5O12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. (C) 2013 Elsevier BY. All rights reserved.

Mots clés: Bismuth iron garnet; Ultrathin film; Magnetization reorientation; Magnetic anisotropy; Pulsed laser deposition

Domaines: Matière Condensée [cond-mat]

Elena Popova, Andres Felipe Franco Galeano, Marwan Deb, Bénédicte Warot-Fonrose, Hamid Kachkachi, et al.. Magnetic anisotropies in ultrathin bismuth iron garnet films. Journal of Magnetism and Magnetic Materials, 2013, 335, pp.139-143. ⟨10.1016/j.jmmm.2013.02.003⟩. ⟨hal-01236757⟩