title: Magneto-Stark effect of excitons as the origin of second harmonic generation in ZnO.
abstract: The magneto-Stark effect of excitons is demonstrated to be an efficient source of optical nonlinearity in hexagonal ZnO. Strong resonant second harmonic generation signals induced by an external magnetic field are observed in the spectral range of 2s and 2p excitons. The microscopic theoretical analysis shows that for excitons with a finite wave vector, exciton states of opposite parity are mixed by an effective odd parity electric field induced by the magnetic field despite its even parity. The field, spectral, and polarization dependencies of the second harmonic generation intensity validate the proposed mechanism. The observed phenomenon is not limited to a certain symmetry class and therefore must be effective in other semiconductors.
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lafrentz
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Brunne
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Kaminski
authors.affiliation: Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
authors.forename: V V
authors.initials: VV
authors.lastname: Pavlov
authors.affiliation: Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
authors.forename: A V
authors.initials: AV
authors.lastname: Rodina
authors.affiliation: Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
authors.forename: R V
authors.initials: RV
authors.lastname: Pisarev
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany and Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia.
authors.forename: D R
authors.initials: DR
authors.lastname: Yakovlev
authors.affiliation: Institut für Halbleitertechnik, Technische Universität Braunschweig, 38106 Braunschweig, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Bakin
authors.affiliation: Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Bayer