Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

Zhang, Ying; Sarma, S. Das

doi:10.1103/physrevb.72.125303

Cited by 31 publications

(19 citation statements)

References 32 publications

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“…On the other hand, the exchange shifts for LH bands may contain sizable corrections due to the neglected interband exchange and the values 52, 62, 126, and 154 meV thus serve only as a rough guide to assess many-body effects on the magneto-optical spectra. These values are similar to the band-gap renormalization [70] used previously [6]. A commonly considered correction to Eq.…”

Section: Appendix B: Microscopic Modelsupporting

confidence: 80%

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Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

et al. 2014

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Magnetic linear dichroism and birefringence in (Ga,Mn)As epitaxial layers is investigated by measuring the polarization plane rotation of reflected linearly polarized light when magnetization lies in the plane of the sample. We report on the spectral dependence of the rotation and ellipticity angles in a broad energy range of 0.12-2.7 eV for a series of optimized samples covering a wide range on Mn dopings and Curie temperatures and find a clear blueshift of the dominant peak at energy exceeding the host material band gap. These results are discussed within the framework of the k · p and mean-field kinetic-exchange model of the (Ga,Mn)As band structure. We infer that disorder-induced nondirect transitions significantly influence magneto-optical properties of (Ga,Mn)As.

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Section: Appendix B: Microscopic Modelsupporting

confidence: 80%

“…The charge density of the delocalized holes is not constant as in the jellium model and this causes an additional band-gap renormalization that can be described by the real part of selfenergy due to hole-acceptor scattering [70]. We estimate it by Eq.…”

Section: Appendix B: Microscopic Modelmentioning

confidence: 99%

Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

et al. 2014

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“…However, stationary 0 is confirmed in this study, indicating that 0 is free of the shrinkage due to carrier-induced exchange and correlation effects 30 as in the band gap. The unaltered HH → SO singularity may originate from transitions through localized states owing to dopants caused potential fluctuations.…”

Section: /∇supporting

confidence: 49%

Direct observation of spin-orbit splitting and phonon-assisted optical transitions in the valence band by internal photoemission spectroscopy

Lao

Perera

et al. 2013

Phys. Rev. B

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We employ internal photoemission spectroscopy to directly measure the valence-band Van Hove singularity, and identify phonons participating in indirect intervalence-band optical transitions. Photoemission of holes photoexcited through transitions between valence bands displays a clear and resolvable threshold, unlike previous reports of interband critical points which become obscure in doped materials. We also demonstrate the enhancement of optical phonon-assisted features primarily contributing to the photoemission yield. This result is evidence of the relaxation of photoexcited hot holes through intravalence-band scatterings in heterojunctions, which contrast with intervalence-band scatterings in bulks.

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“…i. e. lower band gap particles showed higher saturation magnetization and higher band gap particles showed lower saturation magnetization. 56 As discussed above the higher charge carrier concentration leads electrons to get localised to Ti site and reduces its oxidation state further.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

et al. 2015

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In our earlier studies the BaTiO3 samples were processed at higher temperatures like 1000oC and explained the observed magnetism in it. It is found that the charge transfer effects are playing crucial role in explaining the observed ferromagnetism in it. In the present work the samples were processed at lower temperatures like 650oC-800oC. The carrier densities in these particles were estimated to be ∼ 1019-1020/cm3 range. The band gap is in the range of 2.53eV to 3.2eV. It is observed that magnetization increased with band gap narrowing. The higher band gap narrowed particles exhibited increased magnetization with a higher carrier density of 1.23×1020/cm3 near to the Mott critical density. This hint the exchange interactions between the carriers play a dominant role in deciding the magnetic properties of these particles. The increase in charge carrier density in this undoped BaTiO3 is because of oxygen defects only. The oxygen vacancy will introduce electrons in the system and hence more charge carriers means more oxygen defects in the system and increases the exchange interactions between Ti3+, Ti4+, hence high magnetic moment. The coercivity is increased from 23 nm to 31 nm and then decreased again for higher particle size of 54 nm. These particles do not show photoluminescence property and hence it hints the absence of uniformly distributed distorted [TiO5]-[TiO6] clusters formation and charge transfer between them. Whereas these charge transfer effects are vital in explaining the observed magnetism in high temperature processed samples. Thus the variation of magnetic properties like magnetization, coercivity with band gap narrowing, particle size and charge carrier density reveals the super paramagnetic nature of BaTiO3 nanoparticles. The nonlinear optical coefficients extracted from Z-scan studies suggest that these are potential candidates for optical imaging and signal processing applications.

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Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

Cited by 31 publications

References 32 publications

Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

Systematic study of magnetic linear dichroism and birefringence in (Ga,Mn)As

Direct observation of spin-orbit splitting and phonon-assisted optical transitions in the valence band by internal photoemission spectroscopy

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

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