Speaker
Dr
Holger Meyerheim
(Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany)
Description
The talk reviews recent studies on the geometric
structure of oxide films in the ultra thin film limit and their
implications on their magnetic (multiferroic) properties. In
a first example the structural phase transition in pure
and Cobalt-doped ZnO-film is discussed. Depending on
film thickness a transition from the bulk Wurtzite (WZ)-
type structure to the hexagonal-Boron-nitride (h-BN)
phase is observed. Cobalt doping leads to a phase
segregation in which WZ-type CoO-nanoclusters are
coherently embedded into the h-BN host ZnO matrix. The
structure model involving locally confined
antiferromagnetic CoO-clusters supports recent
experimental results on the magnetic properties of
diluted magnetic semiconductors. The effect of
confinement is also decisive for the multiferroic
(ferromagnetic/ferroelectric) properties of the
BaTiO3/Fe(001) interface, which is addressed in the
second part of the talk. The structure analysis in
combination with first principles calculations reveals the
onset of an interface dipole at a critical film thickness of
two unit cells of BaTiO3. Its influence on the
magnetoelectric properties is discussed.
Primary author
Dr
Holger Meyerheim
(Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany)
