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O: Oberflächenphysik

O 34: Oxide und Isolatoren

O 34.3: Vortrag

Donnerstag, 11. März 2004, 11:45–12:00, H45

Ligand Field Approach to Optical Second Harmonic Generation on NiO(001) and CoO(001) surfaces — •Oleksandr Ney and Wolfgang Hübner — Department of Physics, Kaiserslautern University of Technology, Box 3049, 67653 Kaiserslautern

Surfaces and interfaces of transition-metal oxides (TMO) play an important role in technological applications. The strongly correlated 3d-electrons induce interesting effects, however making such materials difficult to describe theoretically. To explore the interfacial properties the optical Second Harmonic Generation (SHG) technique as a nondestructive, easy to implement, and powerful tool may be applied.

In this work we compute the SHG response from the metal ion on the (001) surfaces of NiO and CoO. Calculation of states, active in optical SHG, is performed by using the Hubbard model, Clebsch-Gordan technique, and parametrized ligand field approach. This combination is capable of describing the higher lying states in transition metal oxides. Ionic bonding between metal and oxygen ions is assumed.

As a result, the static dependences of prototypic nonmagnetic and antiferromagnetic (AF) nonlinear susceptibility tensor elements are calculated. Comparison of those spectra gives the energies for which the interference of magnetic and crystallographic contributions may be detected in the SHG experiment, thus allowing to detect the magnetic structure of the interface. Although there are more states within the gap for CoO(001) than for NiO(001), the former one might be as useful for technological applications, which also stimulates further investigations in FeO(001).