A generalized Ginzburg-Landau approach to second harmonic generation
Institut für Physik, Universität Dortmund, 44221 Dortmund, Germany
2 Fachbereich Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany
Published online: 15 March 2000
We develop a generalized Ginzburg-Landau theory for second harmonic generation (SHG) in magnets by expanding the free energy in terms of the order parameter in the magnetic phase and the susceptibility tensor in the corresponding high-temperature phase. The non-zero components of the SHG susceptibility in the ordered phase are derived from the symmetries of the susceptibility tensor in the high-temperature phase and the symmetry of the order parameter. In this derivation, the dependence of the SHG susceptibility on the order parameter follows naturally, and therefore its nonreciprocal optical properties. We examine this phenomenology for the magnetoelectric compound Cr2O3 as well as for the ferroelectromagnet YMnO3.
PACS: 42.65.-k – Nonlinear optics / 75.50.Ee – Antiferromagnetics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000