University
of California, Davis
Physics
Department
Condensed
Matter Seminar
"On the Stabilization of Polar Metal Oxide Surfaces: A First Principles
Study of Fe3O4(001)"
Magnetite
is not only of substantial geological importance but also a potential material
for the development of spintronic devices. However, the structure of the
reconstructed (001)-surface has not been unambiguously resolved to date and is
subject of a controversial debate in the literature. Using ab initio atomistic
thermodynamics [1] we construct a phase diagram of Fe3O4(001) for a variety of
stoichiometric and non-stoichiometric terminations. A modified bulk termination
which has been hitherto ignored based on formal electrostatic criteria is
identified as the lowest energy configuration over a broad range of oxygen
pressures. The DFT-predicted geometry with octahedral iron and oxygen forming a
wave-like structure along the [110]-direction is supported by a x-ray
diffraction analysis [2]. The stabilization of the Fe3O4(001)-surface goes
together with significant changes in the electronic and magnetic properties,
e.g. a halfmetal-to-metal transition.
[1]
K. Reuter and M. Scheffler, Phys. Rev. B 65, 035406, (2002) and references
therein.
[2] R. Pentcheva, F. Wendler, N. Jedrecy, H.L. Meyerheim, W. Moritz, and M. Scheffler, in preparation.
1:00 p.m., 416 Phy/Geo