Regensburg 1998 – wissenschaftliches Programm
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AM: Magnetismus
AM 1: Oberflächenmagnetismus I
AM 1.2: Vortrag
Montag, 23. März 1998, 10:15–10:30, H10
Symmetry Analysis of the Nonlinear Optical Response: Second Harmonic Generation at Surfaces of Antiferromagnets — •M. Trzeciecki1, A. D"ahn2, and W. H"ubner1 — 1Max Planck Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle — 2Institut f"ur Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
Optical Second Harmonic Generation (SHG) has been proven as a powerful technique for the investigation of magnetic surface properties [1]. It is the only optical probe for the imaging of antiferromagnetic domains as demonstrated for example in bulk Cr2O3 [2]. Using symmetry arguments we show how SHG can be used to investigate surfaces of antiferromagnetic materials. Based on the group theoretical analysis of the nonlinear electric susceptibility we propose a nonlinear magneto-optical effect, which allows even in the presence of unit-cell doubling for the unambiguous discrimination of antiferromagnetic surface spin configurations from ferro- or paramagnetic ones. In some important cases the described method allows for the detection of the surface spin configuration even in the presence of lattice distortions and nonmagnetic atoms. As an example, we discuss the polarization dependence of SHG from the fcc (001) surface of NiO in some detail.
[1] M. Straub, R. Vollmer, and J. Kirschner, Phys. Rev. Lett. 77, 743 (1996)
[2] M. Fiebig, D. Fr"ohlich, H-J. Thiele, Phys. Rev. B 54, R12681 (1996)