Second Harmonic Generation in the Centrosymmetric Antiferromagnet NiO

Fiebig, Manfred; Fröhlich, D.; Lottermoser, Thomas; Павлов, В. В.; Pisarev, R. V.; Weber, Helmut

doi:10.1103/physrevlett.87.137202

Cited by 132 publications

(108 citation statements)

References 17 publications

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“…For example, nonlinear optical studies of diamagnetic C 60 fullerene films revealed MD, ED, and EQ mechanisms. 14,15 Other interesting examples are the observations of SHG due to EQ in artificial photonic structures, 16 and due to MD resonances in centrosymmetric antiferromagnets 3,9 and in metamaterials. 17 An important activity of research on SHG and higher order harmonics generation is the search for new mechanisms of nonlinear interaction of light in centrosymmetric and noncentrosymmetric materials, induced by crystallographic and magnetic phase transitions or external perturbations that break the spatial inversion or time reversal symmetry.…”

Section: Introductionmentioning

confidence: 99%

Optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe

et al. 2010

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The magnetic europium chalcogenide semiconductors EuTe and EuSe are investigated by the spectroscopy of second harmonic generation ͑SHG͒ in the vicinity of the optical band gap formed by transitions involving the 4f and 5d electronic orbitals of the magnetic Eu 2+ ions. In these materials with centrosymmetric crystal lattice the electric-dipole SHG process is symmetry forbidden so that no signal is observed in zero magnetic field. Signal appears, however, in applied magnetic field with the SHG intensity being proportional to the square of magnetization. The magnetic field and temperature dependencies of the induced SHG allow us to introduce a type of nonlinear optical susceptibility determined by the magnetic-dipole contribution in combination with a spontaneous or induced magnetization. The experimental results can be described qualitatively by a phenomenological model based on a symmetry analysis and are in good quantitative agreement with microscopic model calculations accounting for details of the electronic energy and spin structure.

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Section: Introductionmentioning

confidence: 99%

Optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe

et al. 2010

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“…The resulting vertex corrections are known to result in deep excitonic states, for example, in NiO. 21 While excitons do not form in FeGe the local vertex corrections should still be important and may cause the observed shift of the main absorption features.…”

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Optical evidence for heavy charge carriers in FeGe

et al. 2007

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The optical spectrum of the cubic helimagnetic metal FeGe has been investigated in the frequency range from 0.01 to 3.1 eV for different temperatures from 30 to 296 K. The optical conductivity shows the evolution of a low-energy ͑0.22 eV͒ interband transition and the development of a narrow free-carrier response with a strong energy and temperature dependence. The frequency-dependent effective mass and scattering rate derived from the optical data indicate the formation of dressed quasiparticles with a mass renormalization factor of 5. Similar to FeSi the spectral weight in FeGe is not recovered over a broad frequency range, an effect usually attributed to the influence of the on-site Coulomb interaction. DOI: 10.1103/PhysRevB.75.155114 PACS number͑s͒: 78.20.Ϫe, 71.27.ϩa, 75.10.Lp, 75.50.Bb Cubic FeGe is a good metal at low temperature, which undergoes a transition to helimagnetic order 1 at T C = 280 K with the magnetic moment at the iron sites of 1 B . The helix changes its orientation in a temperature interval T 2 ±20 K and shows pronounced temperature hysteresis 2 between 211 and 245 K. This material crystallizes in the B20 structure and the cubic space group P2 1 3 lacking a center of symmetry which is responsible for this long-range order. The isoelectronic compound FeSi has the same crystal structure. It has a large magnetic susceptibility at room temperature, which vanishes as the temperature approaches zero due to a small ͑70 meV͒ semiconductor gap at E F . A continuous series FeSi 1−x Ge x can be formed, where the metal insulator transition 3 occurs for x Ϸ 0.25. Theoretical models, which have been proposed to explain this behavior, invoke disorder, 4 narrow bands, and different ways of incorporating electron correlations.5-8 The temperature-dependent disappearance of the gap has been explained as a result of a correlation gap using a two-band Hubbard model, 9,10 and excellent agreement was obtained with optical data, 10-12 but it has been shown that vibrational disorder, if sufficiently strong, also closes the gap. 13 Anisimov et al. 14 have predicted a magnetic-field-driven semiconductor to metal transition in FeSi 1−x Ge x , and argued that the difference in electronic structure between FeSi and FeGe in essence consists of a rigid relative shift of the majority and minority-spin bands for the latter material. According to this model the optical spectra at low energies are expected to be the superposition of a Drude peak and an interband transition across an energy range corresponding to the forementioned relative shift of the majority and minority bands. Experimentally relatively little is known about the electronic structure of FeGe, for example, no optical data have been published.Here, we report optical measurements on a cubic FeGe single crystal at different temperatures. The real and imaginary parts of the dielectric function were derived from the reflectivity and ellipsometry measurements. Optical spectra of FeGe reveal the presence of an important interband transition at 0.22 eV and unusu...

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“…The enhancement of SHG near an optical resonance makes it a sensitive probe of electronic energy levels including d-d transitions [21][22][23] . Since SHG spectra are affected by symmetry changes, the spectra should be distinct for the paramagnetic, antiferromagnetic, and spin-flop phases.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure and magnetic symmetry in MnTiO3analyzed by second harmonic generation

et al. 2013

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Second harmonic generation (SHG) and linear absorbance spectra of MnTiO3 were measured and the 1.88, 2.41, 2.63, and 3.06 eV SHG features were identified as d-d optical transitions from 6 A1g to 4 T1g( 4 G), 4 T2g( 4 G), { 4 Eg, 4 A1g( 4 G)}, and 4 Eg( 4 D) respectively. These zero-phonon transitions were used to calculate the octahedral crystal field splitting energy (∆0) and the Racah parameters B and C. The SHG spectra showed significant distinctions between the antiferromagnetic and the paramagnetic or spin-flop phases. The polarization dependence of the SHG in the spin-flop phase provided optical evidence that the spins canted from the c-axis toward the a-axis. These distinctions between the three magnetic phases could be useful for mapping 180 • antiferromagnetic domains in MnTiO3.2

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Second Harmonic Generation in the Centrosymmetric Antiferromagnet NiO

Cited by 132 publications

References 17 publications

Optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe

Optical second harmonic generation in the centrosymmetric magnetic semiconductors EuTe and EuSe

Optical evidence for heavy charge carriers in FeGe

Electronic structure and magnetic symmetry in MnTiO3analyzed by second harmonic generation

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