ELECTRON-PHONON INTERACTION IN N-DOPED CUPRATES: AN INELASTIC X-RAY SCATTERING STUDY

Inelastic x-ray scattering (IXS) with very high (meV) energy resolution has become a valuable spectroscopic tool, complementing the well established coherent inelastic neutron scattering (INS) technique for phonon dispersion investigations. In the study of crystalline systems IXS is a viable alternative to INS, especially in cases where only small samples are available. Using IXS, we have measured the phonon dispersion of Nd1.86Ce0.14CuO4 + δ along the [ξ, 0, 0] and [ξ, ξ, 0] in-plane directions. Compared to the undoped parent compound, the two highest longitudinal optical (LO) phonon branches are shifted to lower energies because of Coulomb-screening effects brought about by the doped charge carriers. An additional anomalous softening of the highest branch is observed around q = (0.2, 0, 0). This anomalous softening, akin to what has been observed in other compounds, provides evidence for a strong electron-phonon coupling in the electron-doped high-temperature superconductors.

Download Full-text

Phonon dispersion curves in α-SiO2 and hcp 3He and 4He determined by inelastic X-ray scattering

Physica B Condensed Matter ◽

10.1016/s0921-4526(98)01399-4 ◽

1999 ◽

Vol 263-264 ◽

pp. 412-415 ◽

Cited By ~ 14

Author(s):

E Burkel ◽

C Seyfert ◽

Ch Halcoussis ◽

H Sinn ◽

R.O Simmons

Keyword(s):

Phonon Dispersion ◽

Dispersion Curves ◽

Phonon Dispersion Curves ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

Download Full-text

Anomalous Dispersion of Longitudinal Optical Phonons inNd1.86Ce0.14CuO4+δDetermined by Inelastic X-Ray Scattering

Physical Review Letters ◽

10.1103/physrevlett.88.167002 ◽

2002 ◽

Vol 88 (16) ◽

Cited By ~ 76

Author(s):

M. d'Astuto ◽

P. K. Mang ◽

P. Giura ◽

A. Shukla ◽

P. Ghigna ◽

...

Keyword(s):

Longitudinal Optical ◽

Anomalous Dispersion ◽

Optical Phonons ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

Download Full-text

LATTICE DYNAMICS OF CALCIUM FLUORIDE: PART I. LYDDANE, SACHS, TELLER FORMULA, DIFFUSE X-RAY SCATTERING, AND SPECIFIC HEAT

Canadian Journal of Physics ◽

10.1139/p62-007 ◽

1962 ◽

Vol 40 (1) ◽

pp. 74-90 ◽

Cited By ~ 61

Author(s):

S. Ganesan ◽

R. Srinivasan

Keyword(s):

Specific Heat ◽

Calcium Fluoride ◽

Inelastic Neutron Scattering ◽

Interaction Force ◽

Inelastic Neutron ◽

Symmetry Operation ◽

Absorption Frequency ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

The reported violation of the Lyddane, Sachs, Teller formula in calcium fluoride has been shown to arise from an error due to the non-application of a symmetry operation in the second neighbor fluorine–fluorine interaction in Cribier's work. By correct deduction of the force constants, the diffuse X-ray scattering measurements are shown to be in accord with the Lyddane, Sachs, Teller formula, but the specific heat calculation on this model is in disagreement with the experimental data.Reflection measurements in the infrared and dispersion of refractive index are shown to be consistent with the principal infrared absorption frequency near 40 μ and not near 51 μ as assumed in the previous model. The calculation of the specific heat using this new infrared frequency agreed with the measurements only at very low and very high temperatures.The two curves are brought into agreement by assuming that the non-Coulomb cross interaction force constant β1 between first neighbor calcium and fluorine decrease with the wave vector. The diffuse X-ray scattering was recalculated on the model, which explained the specific heat data, and was again found to be in agreement with the Lyddane, Sachs, Teller formula. It is suggested that detailed infrared and inelastic neutron scattering studies be made on this crystal.

Download Full-text