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MA: Fachverband Magnetismus

MA 29: Magnetic Semiconductors I

MA 29.3: Vortrag

Donnerstag, 25. März 2010, 15:45–16:00, H22

Ab-initio study of zinc oxide surfaces and interfaces in presence of cobalt clusters — •Sanjeev K. Nayak, Heike C. Herper, and Peter Entel — University of Duisburg-Essen, 47057 Duisburg, Germany

The magnetic properties of Co doped ZnO are controversially discussed in both theory and experiment. Cationic substitution of Co in ZnO bulk shows ferromagnetic properties only if the concentration of Co exceeds the percolation threshold. The Curie temperature is always below room temperature (RT). In order to enhance the Curie temperature above RT, which is necessary for spintronics applications, lattice defects and the ZnO surfaces play an important role. In addition, not only doped bulk ZnO is of interest but also ZnO nanoclusters with embedded Co clusters.

In this contribution we present results of migration of single doped Co atom and of small Co clusters from the center of ZnO to the surface. This self-purification is of primary interest and hindering successful doping of ZnO nanomaterials [1,2]. We investigate various ZnO surfaces and their structural and magnetic properties in presence of Co impurities. In particular clustering effects over the ZnO surfaces will be discussed.

[1] M. Opel et al., Eur. Phys. J. B, 63, 437 (2008), [2] G. M. Dalpian et al., Phys. Rev. Lett. 96, 226802 (2006)