Hamburg 2001 – wissenschaftliches Programm

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AM: Magnetismus

AM 9: Poster: Magnetowid. (1-17), Dü. Schichten (18-34), Oberfl
ächenmag. (35,36), Mikr. Methoden (37-45), Mikromag. (46-58), Phasenüberg. (59-77), Spektroskop. (78-91), Nanokr.Mat.(92-96), Anisotrop. (97-101), Schmelzen(102-104),Sonst/postdeadl.(105-109)

AM 9.81: Poster

Dienstag, 27. März 2001, 14:45–19:00, Foyer S 3

Near band gap nonlinear spectroscopy of magnetic garnet films — •V.V. Pavlov¹, R.V. Pisarev¹, M. Fiebig², and D. Fröhlich² — ¹Ioffe Physical Technical Institute, 194021 St. Petersburg, Russia — ²Institut für Physik, Universität Dortmund, 44221 Dortmund

Magnetic garnets like the well known Y₃Fe₅O₁₂ crystallize in the structure having centrosymmetric point group m3m. Thin films of bismuth substituted garnets (YBi)₃(FeGa)₅O₁₂ can have a noncentrosymmetric crystallographic structure due to nonuniform distortions or due to a selective distribution of ions in the unit cell during the growth process. This symmetry breaking was proven by observations of the linear magnetoelectric effect and second harmonic generation (SHG) in garnet films. In addition a magnetization-induced contribution to the SHG can be found. In this work we present a spectroscopic study SHG in bismuth substituted garnet films with different crystallographic orientations in the spectral range 1.6−3.4 eV. Using the rotational anisotropy method an unambiguous separation of crystallographic and magnetic contribution to SHG was achieved. Strong enhancement of SHG response was found in the spectral region of the d-d transitions near the band gap. Bismuth substitution of yttrium in the garnet films gives rise to the appearance of a peak at 2.4 eV in the SHG spectra. At energies close to the d−d transitions and the band gap crystallographic and magnetization-induced contributions to SHG have intensities of the same order of magnitude.

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