title: Second harmonic generation in the centrosymmetric antiferromagnet NiO.
abstract: In spite of the fact that inversion is a symmetry operation of both the crystalline and the magnetic lattice of NiO, second harmonic generation (SHG) has been observed below the Néel temperature. A spectroscopic study shows that the signal is due to combined magnetic-dipole and electric-dipole transitions between the (3d)(8) levels of the Ni(2+) ion in the crystal field. The SHG is resonant in both the incoming and the outgoing light waves and thus greatly enhanced. A quadratic coupling of the nonlinear polarization to the order parameter was found. This allows the investigation of individual domains.
authors.affiliation: Institut für Physik, Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Fiebig
authors.forename: D
authors.initials: D
authors.lastname: Fröhlich
authors.forename: T
authors.initials: T
authors.lastname: Lottermoser
authors.forename: V V
authors.initials: VV
authors.lastname: Pavlov
authors.forename: R V
authors.initials: RV
authors.lastname: Pisarev
authors.forename: H J
authors.initials: HJ
authors.lastname: Weber