Many‐body effects in antiferromagnetic 4f‐systems

Bulk, G.; Nolting, Wolfgang

doi:10.1002/pssb.2221400127

Cited by 3 publications

(1 citation statement)

References 20 publications

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“…For I > 0, the localized-spin magnetization and the electron-spin polarization increase, whereas for I < 0, they decrease with increasing the conduction band width [11]. The temperature and carrier concentration dependence of the conduction electron spin polarization for 4f and 5f compounds was discussed in [12,13]. Woolsey and White [14] calculated the electron and magnon lifetime as a function of the doping in the low-temperature spin wave approximation for the FM s-f exchange.…”

Section: Introductionmentioning

confidence: 99%

Competition between Electron–Phonon and Spin–Phonon Interaction on the Band Gap and Phonon Spectrum in Magnetic Semiconductors

Apostolov,

Apostolova,

Wesselinowa

2024

Applied Sciences

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Using the microscopic s-f model and Green’s function theory, we study the temperature dependence of the band gap energy Eg and the phonon energy ω and damping γ of ferro- and antiferromagnetic semiconductors, i.e., with different signs of the s-f interaction constant I. The band gap is a fundamental quantity which affects various optical, electronic and energy applications of the materials. In the temperature dependence of Eg and the phonon spectrum, there is a kink at the phase transition temperature TC or TN due to the anharmonic spin–phonon interaction (SPI) R. Moreover, the effect of the SPI R and electron–phonon interaction (EPI) A on these properties is discussed. For I>0,R>0, Eg decreases with increasing SPI and EPI, whereas for I<0,R>0, there is a competition; Eg increases with raising the EPI and decreases for enhanced SPI. For R<0, in both cases, the SPI and EPI reduce Eg. The magnetic field dependence of Eg for the two signs of I and R is discussed. The SPI and EPI lead to reducing the energy of the phonon mode ω = 445 cm−1 in EuO (I>0, R<0), whereas ω = 151 cm−1 in EuSe (I>0, R>0) is enhanced with increasing EPI and reduced with SPI. Both the SPI and EPI lead to an increasing of the phonon damping in EuO and EuSe. The results are compared with the existing experimental data.

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Section: Introductionmentioning

confidence: 99%

Competition between Electron–Phonon and Spin–Phonon Interaction on the Band Gap and Phonon Spectrum in Magnetic Semiconductors

Apostolov,

Apostolova,

Wesselinowa

2024

Applied Sciences

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Influence of the Band Occupation on the Electronic Damping in the s‐f Model

Wesselinowa

1988

Physica Status Solidi (b)

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The fundamental element in the theory of the so-called s-f model which i s widely accepted as a good description of magnetic 4f-or 5f-systems i s the exchange coupling (s-f coupling) between the conduction band electrons and the lattice of localized magnetic moments. The s-f coupling influences optical, electrical, and magnetic properties of these materials. A s first pointed out by Shastry and Mattis /1/ the physical properties depend very strongly on the sign of the s-f exchange. In the Eu chalcogenides a s well as in Cd theelectron spin couples ferromagnetically (FM) to the f spin /2/, whereas i n the actinide compounds such a s the uranium chalcogenides the s-f coupling seems to be antiferromagnetic (AFM) /3 to 5/.The temperature and carrier concentration dependence of the conduction electron spin polarization for 4f-and 5f-compounds was discussed by many authors /6 to 8/. Nolting and Ole8 /9/ determined the n-dependence of the Curie temperature TC of Gd-doped EuO and E S . Woolsey and White /lo/ calculated the electron and magnon lifetime as function of the doping in the lowtemperature spin-wave approximation for FM s-f exchange.In fact the imaginary parts of the energies corresponding to lifetime broadening effects a r e not considered till now. In our previous papers /11, 12/ (hereafter referred to a s I and II) using a Green function methoa proposed by Tserkovnikov /13/ w e have extended the theory to higher order, and calculated for the first time beyond the RPA t h e electronic spectrum and the damping of

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Antiferromagnetism in 4f-systems with valence instabilities

Bulk

Nolting

1988

Z. Physik B - Condensed Matter

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Many‐body effects in antiferromagnetic 4f‐systems

Cited by 3 publications

References 20 publications

Competition between Electron–Phonon and Spin–Phonon Interaction on the Band Gap and Phonon Spectrum in Magnetic Semiconductors

Competition between Electron–Phonon and Spin–Phonon Interaction on the Band Gap and Phonon Spectrum in Magnetic Semiconductors

Influence of the Band Occupation on the Electronic Damping in the s‐f Model

Antiferromagnetism in 4f-systems with valence instabilities

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