Inelastic scattering of synchrotron radiation from electrons and nuclei for lattice dynamics studies (original) (raw)
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Physica B: Condensed Matter, 2002
Inelastic X-ray scattering (IXS) with meV energy resolution has become a valuable spectroscopic tool in the last 10 years, complementing the well-established coherent inelastic neutron scattering (INS) techniques. In the study of crystalline systems, IXS is the tool of choice in cases where either samples are available only in small quantities or where samples are studied under very high pressure. At the European Synchrotron Radiation Facility (ESRF), there are currently two beam-lines (ID16 and ID28) dedicated to phonon spectroscopy. In order to illustrate the present state of the art, we present two experiments that have been recently performed on the two beam-lines.
Phonon Density of States Measured by Inelastic Nuclear Resonant Scattering
Physical Review Letters, 1995
The phonon density of states was measured by observing the nuclear resonant fluorescence of 57 Fe versus the energy of incident x rays from a synchrotron radiation beam. An energy resolution of 6 meV was achieved by use of high-resolution crystal optics for the incident beam. Extremely low background levels were obtained via time discrimination of the nuclear fluorescent radiation.
Observation of phonons with resonant inelastic x-ray scattering
Journal of Physics-condensed Matter, 2010
Phonons, the quantum mechanical representation of lattice vibrations, and their coupling to the electronic degrees of freedom are important for understanding thermal and electric properties of materials. For the first time, phonons have been measured using resonant inelastic x-ray scattering (RIXS) across the Cu K-edge in cupric oxide (CuO). Analyzing these spectra using an ultra-short core-hole lifetime approximation and exact diagonalization techniques, we can explain the essential inelastic features. The relative spectral intensities are related to the electron-phonon coupling strengths.
Determination of Phonon Dispersions from X-Ray Transmission Scattering: The Example of Silicon
Physical Review Letters, 1999
A beam of monochromatic synchrotron x-ray incident on a silicon wafer creates a rich intensity pattern behind the wafer that reflects the cross section of scattering by thermally populated phonons. A least-squares fit of the patterns based on a lattice dynamics calculation yields the phonon dispersion relations over the entire reciprocal space. This simple and efficient method is suitable for phonon studies in essentially all materials, and complements the traditional neutron scattering technique. PACS numbers: 78.70.Ck, 63.20.Dj Phonons are the fundamental quanta of lattice vibration in a solid. They play a critical role in phenomena such as superconductivity and many types of phase transitions, and are the basis for the acoustic, thermal, elastic, and infrared properties of solids . A fundamental description of phonons is the dispersion relation, which is determined traditionally through neutron scattering or, more recently, through inelastic x-ray scattering . However, these methods can be technically demanding, and alternative, complementary methods have been long sought. This study demonstrates a new approach based on x-ray intensity patterns produced by scattering from thermally populated phonons using silicon as a test case. Intensity patterns with a wide dynamic range were recorded in a matter of seconds at the third-generation synchrotron, the Advanced Photon Source. A least-squares analysis in terms of lattice dynamics yields dispersions for all six phonon branches in excellent agreement with neutron scattering results. The fast data acquisition rate, simplicity of the experiment, and a minimal requirement on sample volume make this method attractive for a wide range of applications in materials research.
Determination of Phonon Dispersion Curves at Gigapascal Pressures by Inelastic X-ray Scattering
High Pressure Research, 2002
The study of phonon dispersion curves of materials under hydrostatic pressure provides important information such as the evolution of sound velocities, elastic constants, interatomic potentials, phase transition mechanisms, etc. Until very recently, coherent inelastic neutron scattering was the only spectroscopic technique, which allowed performing these types of studies up to typically 10 GPa. Today, inelastic X-ray scattering with meV energy resolution provides a complementary spectroscopic technique, where, using diamond anvil cell techniques, pressures beyond 100 GPa can be reached.
2010
We show that high resolution Resonant Inelastic X-ray Scattering (RIXS) provides direct, elementspecific and momentum-resolved information on the electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates that the e-p coupling can be extracted from RIXS spectra by determining the differential phonon scattering cross section. An alternative, very direct manner to extract the coupling is to use the one and two-phonon loss ratio, which is governed by the e-p coupling strength and the core-hole life-time. This allows measurement of the e-p coupling on an absolute energy scale. PACS numbers: 78.70.Ck
Physical Review X, 2021
degrees of freedom, while angle-resolved photoemission spectroscopy (ARPES) [7] measures it via the electronic self-energy. In other far-from-equilibrium situations, however, the interaction between phonons and electrons away from the Fermi surface becomes important. This regime applies to processes such as high-temperature heat transport [8], high-field electrical transport [9], and phononassisted optical transitions [10, 11], with applications in optoelectronics [12, 13], for example. The established probes of e-ph coupling, listed above, are generally unable to access such highly excited electronic states, particularly if information is required about the interaction with phonon modes of specific momenta. Recently, RIXS has been gaining traction as a new technique to measure the e-ph interaction strength, which manifests directly in the intensity of the phonon excitations. Over the last decade, improvements in energy resolution have enabled experimental studies on a growing number of materials [14-27], alongside an ad
Coherent x-ray scattering by phonons: Determination of phonon eigenvectors
Physical Review Letters, 1988
Interference effects have been observed when coherently coupled x-ray beams are inelastically scattered by phonons in a crystal. The coherently coupled beams are prepared by dynamical diffraction methods. This principle was applied to determine the phases of the phonon eigenvectors in silicon by an analysis of the intensity of the inelastically scattered x rays.
Low-lying phonons inNaBH4studied by inelastic scattering of synchrotron radiation
Physical Review B, 2008
Acoustic phonon dispersion has been measured in the cubic phase of NaBH 4 by the inelastic x-ray scattering ͑IXS͒ technique using single crystals of natural isotope composition at room temperature. Experimental results are compared with the compressibility data and the previously published ab initio calculations. Comparison of the elastic properties derived from the diffraction and IXS experiments indicates a non-negligible contribution ͑below 10%͒ of nonhydrostatic effects in the diffraction experiments. Strong preferred orientation in the compressed samples is also revealed by Rietveld analysis of the synchrotron powder-diffraction data.
Direct Observation of Chiral Phonons by Inelastic X-ray Scattering
2021
Qingan Cai, Olle Hellman, Bin Wei, Qiyang Sun, Ayman H. Said, Thomas Gog, Barry Winn, and Chen Li Department of Mechanical Engineering, University of California at Riverside, Riverside, CA 92521 Materials Science and Engineering, University of California at Riverside, Riverside, CA 92521 Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden Henan Key Laboratory of Materials on Deep-Earth Engineering, School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 Neutron Scattering Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (Dated: August 17, 2021)