High resolution inelastic X-ray scattering from thermal collective excitations

d’Astuto, Matteo; Krisch, M.

doi:10.1051/sfn/2010010

Cited by 5 publications

(2 citation statements)

References 36 publications

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“…3 shows representative IXS spectra for three different directions, longitudinal along (q q 0), with Σ 1 character, longitudinal along the (q 0 0) direction, with ∆ 1 character and transverse along the equivalent (0 q 0) direction, with ∆ 3 character, for the same value In Ca 2−x CuO 2 Cl 2 the contrast between the elastic line and the low energy mode on one side and high energy mode on the other, it is not as strong as in other cuprates. The ratio is determined by the ions number of electrons, as the the IXS scattering yield is proportional to Z 2 and the photoelectron absorption to Z 4 , so that the high Z elements dominate in a system with different atomic species, while the high energy mode come almost exclusively from light element vibrations 32 . In other cuprate systems, measuring the high energy mode dispersion is therefore possible only at few (∼ 10) Kelvin, where the Bose factor is strongly reduced for modes below 25 meV, compared to the intensity at room temperature 33 .…”

Section: A Crystal Growth and Characteristicsmentioning

confidence: 99%

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
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We present a comprehensive study of the phonon dispersion in an underdoped, superconducting Ca 2−x CuO 2 Cl 2 crystal. We interpret the results using lattice dynamical calculations based on a shell model, and we compare the results, to other hole-doped cuprates, in particular to the ones isomorphic to La 2−x Sr x CuO 4 (LSCO). We found that an anomalous dip in the Cu-O bond stretching dispersion develops in oxychlorides with a simultaneous marked broadening of the mode. The broadening is maximum at ≈ (π/(2a) 0 0) that corresponds to the charge-modulations propagation vector. Our analysis also suggests that screening effects in calculations may cause an apparent cosine-shaped bending of the Cu-O bond-stretching dispersion along both the (q 0 0) and (q q 0) directions, that is not observed on the data close to optimal doping. This observation suggests that the discrepancy between experimental data and ab-initio calculations on this mode originates from an overestimation of the doping effects on the mode. PACS numbers: 74.72.Gh, 63.20.D-, 63.20.kd, 78.70.Ck 1 arXiv:1305.6719v3 [cond-mat.str-el] 5 Jun 2013 I. INTRODUCTIONThe discovery of high temperature superconductivity (HTS) in cuprates was originally motivated by the search for superconductors with strong electron-phonon coupling 1 . The first HTS compounds, La 2−x Ba x CuO 4 (LBCO) and LSCO, do indeed display a very large isotopic effect for oxygen, although the doping dependence of this effect turns out to be very anomalous 2 . Later studies pointed out that electron-phonon coupling may not be the main origin of the Cooper pairing 3 , in particular for optimal doping. But its role across the phase diagram of cuprates is still controversial, in particular in its under-doped region.An important point is that single electron band approximations, such as Density Functional Theory (DFT) find a small electron-phonon coupling 4,5 , but they possibly miss many body effects, as it was suggested that large couplings may exist in the presence of strong electronelectron correlations 6 .An important point stressed in DFT based investigations on electron-phonon coupling in cuprates is that these calculations seem to reproduce well the marked softening with a cosine dispersion, that develops under doping for longitudinal Cu-O bond-stretching mode along the direction (q 0 0) of such bonds (modes with ∆ 1 character). At the same time, large discrepancies between those calculations for the same mode, but along the diagonal direction (q q 0) (modes with Σ 1 character) are found 4,7 . It has been suggested that the physical origin of the anomaly in the dispersion of the Cu-O bond-stretching modes is different for the two directions 4,5 .Underdoped cuprates exhibit a static, or quasi-static, modulation of the charge, characterized by a stripe pattern parallel to the Cu-O bonds, which can give clear diffraction peaks both in the charge 8,9 and spin channel, for doping close to δ ∼ 1/8 with a propagation vector of ≈ π/(2a), i.e. a periodicity of ≈ 4a, where a is the lattice parameter...

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Section: A Crystal Growth and Characteristicsmentioning

confidence: 99%

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
View full text Add to dashboard Cite

show abstract

“…A weak temperature dependence of the intensities can be noticed but nothing that would go beyond expected an-harmonic effects. Here we may suggest a future experiment, using inelastic Xray scattering, which has a constant and better resolution compared with thermal neutron scattering at such a high energy exchange [31], to seek for a possible broadening of the phonon modes.…”

Section: Phonon Spectrummentioning

confidence: 99%

Experimental study of spinon-phonon coupling in spin-chain cuprates

et al. 2023

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In this paper, we focus on the thermal transport properties of antiferromagnetic spin chains cuprates. The chain magnetic excitations, the spinons, partake in heat transport at low temperature, but spinon heat transport decays well below room temperature, possibly because of a coupling with phonons. By means of inelastic neutron scattering, we thoroughly study the lattice dynamics of spin chain compounds Sr2CuO3, Ca2CuO3, along with double spin-chain compounds SrCuO2. We come to the conclusion that there are no obvious anomalies in the phonon dispersions, which suggests a weak spinon-phonon coupling regime.

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LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations

Togo

Hayashi

Tadano

et al. 2022

J. Phys.: Condens. Matter

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Longitudinal-optical (LO) mode phonon branches of KCl and NaCl were measured using inelastic X-ray scattering (IXS) at 300 K and calculated by the ﬁrst-principles phonon calculation with the stochastic self-consistent harmonic approximation. Spectral shapes of the IXS measurements and calculated spectral functions agreed well. We analyzed the calculated spectral functions that provide higher resolutions of the spectra than the IXS measurements. Due to strong anharmonicity, the spectral functions of these phonon branches have several peaks and the LO modes along Γ–L paths are disconnected.

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High resolution inelastic X-ray scattering from thermal collective excitations

Cited by 5 publications

References 36 publications

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
View full text Add to dashboard Cite

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
View full text Add to dashboard Cite

Experimental study of spinon-phonon coupling in spin-chain cuprates

LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations

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High resolution inelastic X-ray scattering from thermal collective excitations

Cited by 5 publications

References 36 publications

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cld’Astuto1, Yamada2, Giura3 et al. 2013Phys. Rev. B152100View full textAdd to dashboardCite

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cld’Astuto1, Yamada2, Giura3 et al. 2013Phys. Rev. B152100View full textAdd to dashboardCite

Experimental study of spinon-phonon coupling in spin-chain cuprates

LO-mode phonon of KCl and NaCl at 300 K by inelastic x-ray scattering measurements and first principles calculations

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Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
View full text Add to dashboard Cite

Phonon anomalies and lattice dynamics in the superconducting oxychlorides Ca2−xCuO2Cl
d’Astuto
¹
,
Yamada
²
,
Giura
³

et al. 2013
Phys. Rev. B
15
2
10
0
View full text Add to dashboard Cite