Modeling the dichroic absorption band edge and light-induced magnetism in EuTe

Henriques, A. B.; Manfrini, Mauricio; Rappl, P. H. O.; Abramof, E.

doi:10.1103/physrevb.77.035204

Cited by 24 publications

(47 citation statements)

References 24 publications

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“…62,82,83 In the present work, we shall use the 4f 7 ͑ 8 S 7/2 ͒ → 5d͑t 2g ͒ model to interpret the optical nonlinearities observed in EuX.…”

Section: -81mentioning

confidence: 99%

“…[66][67][68][69][70][71][72][73] The lowest-energy conduction band has a narrow width of ϳ100 meV, 61,62 so that it can be described by a tight-binding model. The basis set of the tight-binding wave functions consists of the 5d orbitals of the Eu atoms, split by the octahedral crystal field into a twofold degenerate lowenergy 5d͑t 2g ͒ state, and a 5d͑e g ͒ state at about 2 eV higher energy.…”

Section: B Electronic Band Structurementioning

confidence: 99%

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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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“…62,82,83 In the present work, we shall use the 4f 7 ͑ 8 S 7/2 ͒ → 5d͑t 2g ͒ model to interpret the optical nonlinearities observed in EuX.…”

Section: -81mentioning

confidence: 99%

Section: B Electronic Band Structurementioning

confidence: 99%

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

et al. 2010

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“…The superior quality of EuTe grown by MBE is demonstrated by its improved optical properties, e.g., new band-edge absorption of unprecedent sharpness [17], narrow photoluminescence (PL) lines at higher energies than ever seen before [18], novel second-harmonic generation [19], and a rich spectrum of magneto-refractive effects previously unknown [20]. Based on these discoveries, it became possible to successfully describe the EuTe band-edge electronic structure in the framework of one-electron band theory [21,22], whose validity in rare-earth oxides was questioned in the past [23] due to divergences between theory and the experimental data available at the time [24]. MBE can also be used to integrate Eu chalcogenides into a silicon substrate and other III-V semiconductor structures [25,26], which enhances the prospects of using EuTe in novel optospintronic devices.…”

Section: Introductionmentioning

confidence: 99%

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

et al. 2014

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The recent discovery of a polaron-associated zero phonon line in the band-edge photoluminescence of high optical quality EuTe crystals opens up the prospect of answering long-standing questions about the polaron internal structure, thermal stability, and generation efficiency. Here, a Schrödinger equation for the polaron was formulated and resolved by using both variational and self-consistent methods. The theory is in good agreement with measurements of the zero phonon line as a function of magnetic field and temperature, and it could be applied to other polaronic systems. It is deduced that, in EuTe, at 0 K, a polaron carries a magnetic moment of 610μ B , and its binding energy is 27 meV. However, this binding energy does not carry the usual meaning of thermal stability, because it decreases drastically when the sample is warmed up. For instance, at T = 100 K, the binding energy is already reduced to only 6 meV. The thermal destruction of a polaron is brought about by thermal fluctuations of the spin lattice that suppress the electron's self-energy. Photoluminescence excitation spectra of EuTe demonstrate that the photogeneration of polarons becomes increasingly inefficient when the energy of the pumping photon is increased above the band gap.

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“…In this section we shall examine a THG model in the framework of the electronic structure which describes well the dichroic band-edge optical absorption, [57][58][59] and also the SHG in EuTe. 60 The main purpose is to verify the adequateness of the level scheme to describe the main features of the THG spectrum, and, in particular, to gain an understanding why the THG efficiency is nonzero in zero magnetic field.…”

Section: Discussion and A Quantum-mechanical Model Of Thgmentioning

confidence: 99%

“…͑19͒ involve seven electrons and can be converted into single-electron matrix elements by taking into account spin conservation. 57,59 This is done by performing a Clebsch-Gordan expansion of the 7 F JM states, which is then represented by a series of terms with defined electronic spin. The final result for P x0 ͑3͒ ͑3 ͒ is…”

Section: Discussion and A Quantum-mechanical Model Of Thgmentioning

confidence: 99%

Optical third-harmonic spectroscopy of the magnetic semiconductor EuTe

et al. 2010

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EuTe possesses the centrosymmetric crystal structure m3m of rocksalt type in which the second-harmonic generation is forbidden in electric dipole approximation but the third-harmonic generation ͑THG͒ is allowed. We studied the THG spectra of this material and observed several resonances in the vicinity of the band gap at 2.2-2.5 eV and at higher energies up to 4 eV, which are related to four-photon THG processes. The observed resonances are assigned to specific combinations of electronic transitions between the ground 4f 7 state at the top of the valence band and excited 4f 6 5d 1 states of Eu 2+ ions, which form the lowest energy conduction band. Temperature, magnetic field, and rotational anisotropy studies allowed us to distinguish crystallographic and magnetic-field-induced contributions to the THG. A strong modification of THG intensity for the 2.4 eV band and suppression of the THG for the 3.15 eV band was observed in applied magnetic field. Two main features of the THG spectra were assigned to 5d͑t 2g ͒ and 5d͑e g ͒ subbands at 2.4 eV and 3.15 eV, respectively. A microscopic quantum-mechanical model of the THG response was developed and its conclusions are in qualitative agreement with the experimental results.

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Modeling the dichroic absorption band edge and light-induced magnetism in EuTe

Cited by 24 publications

References 24 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

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

Optical third-harmonic spectroscopy of the magnetic semiconductor EuTe

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