Second Harmonic Generation Spectroscopy And Domain Imaging Of The High-Temperature Multiferroic Cuo

An analysis of the magnetically induced ferroelectric phase in the high-temperature multiferroic CuO by optical second harmonic generation (SHG) reveals a rich variety of contributions coupling to the multiferroic order. Observation of a "giant" SHG efficiency points to the presence of electronic contributions to the spontaneous polarization. The SHG spectra are dominated by transitions within the Cu2+(3d(9)) band and by SHG resonance enhancement. An investigation of the multiferroic domain structure by SHG shows an isotropic distribution of domains with a lateral extension of about 10 mu m. This value is 1-2 orders of magnitude smaller than in other multiferroics and emphasizes the outstanding position CuO takes in the family of magnetically induced ferroelectrics.