Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 81: Oxide and Insulator Surfaces III
O 81.12: Vortrag
Donnerstag, 3. April 2014, 18:45–19:00, PHY C 213
Structure, stress and magnetism of CoO(111) monolayers on Ir(001) — •Sumalay Roy1, Holger Meyerheim1, Katayoon Mohseni1, Zehn Tian1, Dirk Sander1, Arthur Ernst1,2, Martin Hoffmann1,3, Waheed Adeagbo3, Wolfram Hergert3, Roberto Felici4, and Jürgen Kirschner1,3 — 1Max-Planck-Institute of Microstructure Physics, Halle, Germany — 2Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Leipzig, Germany — 3Martin-Luther-University Halle-Wittenberg, Halle, Germany — 4European Synchrotron Radiation Facility, Grenoble, France
To investigate the structural depolarization [1] and its correlation with magnetic properties [2] in ultrathin (111) oriented CoO films, 1.6 and 2 monolayers of CoO were deposited on Ir(001) using molecular beam epitaxy of Co followed by subsequent annealing in ambient oxygen. An in-situ Surface X-ray diffraction (SXRD) measurement and analysis of the so prepared CoO(111) films reveals the coexistence of wurtzite and rocksalt structure involving strong vertical relaxations, which is attributed to the reduction of the dipole moment in the polar CoO (111) film which in the bulk renders the structure unstable. The measured stress change (+2.1 N/m) during epitaxial growth can be attributed to the epitaxial misfit between the c-(10×2) CoO(111) film and the Ir(001) substrate. Ab-initio calculations using the SXRD structure parameters as input reveal an anti-ferromagnetic order (below 150K) in the CoO film. [1] P. W. Tasker J. Phys. C: Solid State Phys. 12, 4977 (1979). [2] F. Mittendorfer et. al., Phys. Rev. Lett. 109, 015501 (2012).