Infrared spectroscopic study of phonons coupled to charge excitations in FeSi

Damascelli, A.; Schulte, Karl‐Wilhelm; Marel, D. van der; Menovsky, A.A.

doi:10.1103/physrevb.55.r4863

Cited by 91 publications

(93 citation statements)

References 16 publications

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“…17 Lastly, we report that no pseudogap due to electron correlation is observed in this material. Most of the pseudogaps in strongly correlated materials, as in a similar 3d metallic alloy FeSi, [18][19][20] have a strong temperature dependence in reflectivity and optical conductivity. In contrast, our FTIR data for Fe 2 VAl show that the concentration and scattering time of free carriers remain nearly constant when the temperature is changed.…”

Section: Ftir Resultsmentioning

confidence: 99%

Physical properties of Heusler-likeFe2VAl

et al. 2001

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A comprehensive characterization of the compound Fe 2 VAl was carried out. Samples grown by arc melting or the Bridgman method have Al and Fe deficiencies of up to 5 at. %. Czochralski-grown samples were Fe rich and Al deficient. X-ray diffraction implies appreciable antisite disorder in all of our samples. Fourier-transform infrared (FTIR) spectroscopy measurements showed that the carrier density and scattering time had little sample-to-sample variation or temperature dependence for near-stoichiometric samples. FTIR and dc resistivity suggest that the transport properties of Fe 2 VAl are influenced by both localized and delocalized carriers, with the former primarily responsible for the negative temperature coefficient of resistivity. Magnetization measurements reveal that near-stoichiometric samples have superparamagnetic clusters with at least two sizes of moments. We conclude that in Fe 2 VAl, antisite disorder causes significant modification to the semimetallic band structure proposed theoretically. With antisite disorder considered, we are now able to explain most of the physical properties of Fe 2 VAl. None of our data suggest heavy-fermion behavior in our samples. A comprehensive characterization of the compound Fe 2 VAl was carried out. Samples grown by arc melting or the Bridgman method have Al and Fe deficiencies of up to 5 at. %. Czochralski-grown samples were Fe rich and Al deficient. X-ray diffraction implies appreciable antisite disorder in all of our samples. Fourier-transform infrared ͑FTIR͒ spectroscopy measurements showed that the carrier density and scattering time had little sample-to-sample variation or temperature dependence for near-stoichiometric samples. FTIR and dc resistivity suggest that the transport properties of Fe 2 VAl are influenced by both localized and delocalized carriers, with the former primarily responsible for the negative temperature coefficient of resistivity. Magnetization measurements reveal that near-stoichiometric samples have superparamagnetic clusters with at least two sizes of moments. We conclude that in Fe 2 VAl, antisite disorder causes significant modification to the semimetallic band structure proposed theoretically. With antisite disorder considered, we are now able to explain most of the physical properties of Fe 2 VAl. None of our data suggest heavy-fermion behavior in our samples. Keywords Physics and Astronomy

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Section: Ftir Resultsmentioning

confidence: 99%

Physical properties of Heusler-likeFe2VAl

et al. 2001

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“…Ref. 17 ), given by σ(ω) = iσ 0 (q−i) 2 ·(i+x) −1 , with x = (ω 2 −ω 2 T )/γω, γ and ω T are the line-width and the resonant frequency, and σ 0 denotes the amplitude which is related to the oscillator strength as S = 4πσ 0 (q 2 − 1)γω −2 T . The dimensionless Fano parameter q = −1/ tan(Θ/2) is a measure of the asymmetry of the peak and for Θ = 0 a Lorentzian line shape is recovered.…”

Section: Resultsmentioning

confidence: 99%

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
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Critical behavior of the infrared reflectivity of RuSr2GdCu2O8 ceramics is observed near the superconducting TSC = 45 K and magnetic TM = 133 K transition temperatures. The optical conductivity reveals the typical features of the c-axis optical conductivity of strongly underdoped multilayer superconducting cuprates. The transformation of the Cu-O bending mode at 288 cm −1 to a broad absorption peak at the temperatures between T * = 90 K and TSC is clearly observed, and is accompanied by the suppression of spectral weight at low frequencies. The correlated shifts to lower frequencies of the Ru-related phonon mode at 190 cm −1 and the mid-IR band at 4800 cm −1 on decreasing temperature below TM are observed. It provides experimental evidence in favor of strong electron-phonon coupling of the charge carriers in the Ru-O layers which critically depends on the Ru core spin alignment. The underdoped character of the superconductor is explained by strong hole depletion of the CuO2 planes caused by the charge carrier self-trapping at the Ru moments.

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“…The full analysis was presented in Ref. [13]. This requires that at least some of the bonds between Fe and Si are incomplete.…”

Section: Resonating Bonds Coupled To Phononsmentioning

confidence: 99%

Spin, charge, and bonding in transition metal mono-silicides

Marel

Damascelli

Schulte

et al. 1998

Physica B: Condensed Matter

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We review some of the relevant physical properties of the transition metal mono-silicides with the FeSi structure (CrSi, MnSi, FeSi, CoSi, NiSi, etc) and explore the relation between their structural characteristics and the electronic properties. We confirm the suggestion orginally made by Pauling, that the FeSi structure supports two quasi-atomic d-states at the transition metal atom. This shell contains from 0 to 4 electrons in the sequence CrSi to NiSi. In FeSi the two quasi-atomic d-electrons are responsible for the high temperature S = 1 state, which is compensated for T=0 by two itinerant electrons associated with the Fe-Si resonance bonds.

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Infrared spectroscopic study of phonons coupled to charge excitations in FeSi

Cited by 91 publications

References 16 publications

Physical properties of Heusler-likeFe2VAl

Physical properties of Heusler-likeFe2VAl

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite

Spin, charge, and bonding in transition metal mono-silicides

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Infrared spectroscopic study of phonons coupled to charge excitations in FeSi

Cited by 91 publications

References 16 publications

Physical properties of Heusler-likeFe2VAl

Physical properties of Heusler-likeFe2VAl

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2OBoris1, Mandal2, Bernhard3 et al. 2001Phys. Rev. B24382View full textAdd to dashboardCite

Spin, charge, and bonding in transition metal mono-silicides

Contact Info

Product

Resources

About

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite