Magnetic and Structural Properties of MBE-grown Oxidic Multilayers

Abstract

AbstractMultilayers composed of oxides including Fe3O4, CoxFe3−x, O4, CoO, NiO and MgO have been grown epitaxially by MBE on MgO(100) single crystal substrates. These structures can be grown with a high crystallinity in the form of flat layers having sharp interfaces. RHEED studies which commonly yielded sharp streaks accompanied by Kikuchi lines show that, for instance, growth of CoO on Fe3O4 changes the RHEED pattern from that consistent with a spinel structure to that of a rocksalt structure within about one and a half unit cell of CoO. STM studies on a 400 Å Fe3O4 layer displaying atomic resolution enabled us to identify the origin of the reconstruction that one commonly observes in the RHEED and LEED patterns for magnetite. Regarding important fundamental magnetic parameters, relevant thickness dependencies were mapped out using localized magneto-optical Kerr effect experiments performed on several samples that routinely included one or multiple wedge shaped layers. These studies revealed the existence of a region in the Fe3O4 layer near the interfaces which exhibits no net magnetic moment, strain driven perpendicular orientated magnetization for the CoO/Fe3O4(100) and CoO/CoxFe3−xO4(100) bilayer systems, and information on the thickness dependence of the magnetic interlayer coupling across an MgO spacer layer.