On possible conical singularities in magneto-optics

Merkulov, V. S.

doi:10.1134/s0021364011170127

Cited by 5 publications

(4 citation statements)

References 8 publications

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“…When applying the electric field, we find that the low lying excitons in the series indeed follow roughly the expected dependence (dashed line in Fig. 12) which according to the theoretical calculations should be given by [22,29]…”

Section: Electric Fieldsupporting

confidence: 57%

Scaling laws of Rydberg excitons

Heckötter¹,

Freitag²,

Fröhlich³

et al. 2017

Phys. Rev. B

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Rydberg atoms have attracted considerable interest due to their huge interaction among each other and with external fields. They demonstrate characteristic scaling laws in dependence on the principal quantum number $n$ for features such as the magnetic field for level crossing. While bearing striking similarities to Rydberg atoms, fundamentally new insights may be obtained for Rydberg excitons, as the crystal environment gives easy optical access to many states within an exciton multiplet. Here we study experimentally and theoretically the scaling of several characteristic parameters of Rydberg excitons with $n$. From absorption spectra in magnetic field we find for the first crossing of levels with adjacent principal quantum numbers a $B_r \propto n^{-4}$ dependence of the resonance field strength, $B_r$, due to the dominant paramagnetic term unlike in the atomic case where the diamagnetic contribution is decisive. By contrast, in electric field we find scaling laws just like for Rydberg atoms. The resonance electric field strength scales as $E_r \propto n^{-5}$. We observe anticrossings of the states belonging to multiplets with different principal quantum numbers. The energy splittings at the avoided crossings scale as $n^{-4}$ which we relate to the crystal specific deviation of the exciton Hamiltonian from the hydrogen model. We observe the exciton polarizability in the electric field to scale as $n^7$. In magnetic field the crossover field strength from a hydrogen-like exciton to a magnetoexciton dominated by electron and hole Landau level quantization scales as $n^{-3}$. The ionization voltages demonstrate a $n^{-4}$ scaling as for atoms. The width of the absorption lines remains constant before dissociation for high enough $n$, while for small $n \lesssim 12$ an exponential increase with the field is found. These results are in excellent agreement with theoretical calculations.Comment: 16 pages, 13 figure

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Section: Electric Fieldsupporting

confidence: 57%

Scaling laws of Rydberg excitons

Heckötter¹,

Freitag²,

Fröhlich³

et al. 2017

Phys. Rev. B

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“…The combination of experiment and theory allows us to demonstrate that (i) the photocarrier distribution anisotropy is stronger for lower radiation intensities when the anisotropic character of the excitation is not yet suppressed by the isotropic Fermi-Dirac sea; (ii) the isotropization dynamics is driven by the carriers' scattering with optical phonons, whereas e-e scattering is mainly responsible for the initial photocarrier redistribution along the Dirac cone. The latter observation is in stark contrast with the case of conventional direct-gap semiconductors, like GaAs [31], where the anisotropies are typically lost via carriercarrier scattering [32,33].…”

mentioning

confidence: 96%

Ultrafast pseudospin dynamics in graphene

et al. 2015

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Interband optical transitions in graphene are subject to pseudospin selection rules. Impulsive excitation with linearly polarized light generates an anisotropic photocarrier occupation in momentum space that evolves at timescales shorter than 100fs. Here, we investigate the evolution of non-equilibrium charges towards an isotropic distribution by means of fluence-dependent ultrafast spectroscopy and develop an analytical model able to quantify the isotropization process. In contrast to conventional semiconductors, the isotropization is governed by optical phonon emission, rather than electron-electron scattering, which nevertheless contributes in shaping the anisotropic photocarrier occupation within the first few fs.

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“…The Coulomb interaction, however, modifies significantly the optical properties due to the formation of correlated electron-hole pairs, and needs to be included. Initial efforts to add these excitonic effects, both numerically and semianalytically, were made within the effective mass approximation; [19][20][21][22][23][24] this simple approximation is still used to analyze experimental data. 25 Rees provided a more complete method to compare theory and experiment, 26,27 including not only the electron-hole interaction but also lattice defects, band anisotropy, lifetime broadening and surface effects.…”

Section: Introductionmentioning

confidence: 99%

The Franz–Keldysh effect revisited: Electroabsorption including interband coupling and excitonic effects

Duque-Gomez¹,

Sipe²

2015

Journal of Physics and Chemistry of Solids

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We study the linear optical absorption of bulk semiconductors in the presence of a homogeneous constant (dc) electric field with an approach suitable for including excitonic effects while working with many-band models. The absorption coefficient is calculated from the time evolution of the interband polarization excited by an optical pulse. We apply the formalism to a numerical calculation for GaAs using a 14-band k · p model, which allows us to properly include interband coupling, and the exchange self-energy to account for the excitonic effects due to the electron-hole interaction. The Coulomb interaction enhances the features of the absorption coefficient captured by the k · p model. We consider the dependence of the enhancement on the strength of the dc field and the polarization of the optical field.

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On possible conical singularities in magneto-optics

Cited by 5 publications

References 8 publications

Scaling laws of Rydberg excitons

Scaling laws of Rydberg excitons

Ultrafast pseudospin dynamics in graphene

The Franz–Keldysh effect revisited: Electroabsorption including interband coupling and excitonic effects

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