Phonon anomaly near a Fermi surface topological transition

Dagens, L.

doi:10.1088/0305-4608/8/10/010

Cited by 71 publications

(18 citation statements)

References 17 publications

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“…41 An ETT causes anomalous signature in mechanical, electrical and thermodynamic properties and it also affects vibrational properties. [41][42] Hence, we interpret the anomaly at around 4 GPa in Sb 2 S 3 can be due to a second order isostructural phase transition called ETT in comparison with similar transition observed in the metal chalcogenide A 2 B 3 series.…”

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confidence: 66%

Pressure-induced electronic topological transition in Sb₂S₃

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Rajaji

Malavi

et al. 2015

J. Phys.: Condens. Matter

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Pressure induced electronic topological transitions in the wide band gap semiconductor Sb 2 S 3 (E g = 1.7-1.8 eV) with similar crystal symmetry (SG: Pnma) to its illustrious analog, Sb 2 Se 3 , has been studied using Raman spectroscopy, resistivity and the available literature on the xray diffraction studies. In this report, the vibrational and the transport properties of Sb 2 S 3 have been studied up to 22 GPa and 11 GPa, respectively. We observed the softening of phonon modes A g (2), A g (3) and B 2g and a sharp anomaly in their line widths at 4 GPa. The resistivity studies also shows an anomaly around this pressure. The changes in resistivity as well as Raman line widths can be ascribed to the changes in the topology of the Fermi surface which induces the electron-phonon and the strong phonon-phonon coupling, indicating a clear evidence of the electronic topological transition (ETT) in Sb 2 S 3 . The pressure dependence of a/c ratio plot obtained from the literature showed a minimum at ~ 5 GPa, which is consistent with our high pressure Raman and resistivity results. Finally, we give the plausible reasons for the non-existence of a non-trivial topological state in Sb 2 S 3 at high pressures.

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confidence: 66%

Pressure-induced electronic topological transition in Sb₂S₃

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Rajaji

Malavi

et al. 2015

J. Phys.: Condens. Matter

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“…Filling it causes a loss of states at the Fermi level and a loss of electrons that can participate in screening. 52 There are a number of discussions about how electronic topological transitions alter physical properties of metals and alloys such as elastic constants [355,356,357,358,359,360]. Electronic topological transitions alter phonons by changing the adiabatic EPI.…”

Section: Kohn Anomalies and Electronic Topological Transitionsmentioning

confidence: 99%

Vibrational thermodynamics of materials

Fultz¹

2010

Progress in Materials Science

558

428

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Abstract. The literature on vibrational thermodynamics of materials is reviewed. The emphasis is on metals and alloys, especially on the progress over the last decade in understanding differences in the vibrational entropy of different alloy phases and phase transformations. Some results on carbides, nitrides, oxides, hydrides and lithium-storage materials are also covered.Principles of harmonic phonons in alloys are organized into thermodynamic models for unmixing and ordering transformations on an Ising lattice, and extended for non-harmonic potentials. Owing to the high accuracy required for the phonon frequencies, quantitative predictions of vibrational entropy with analytical models prove elusive. Accurate tools for such calculations or measurements were challenging for many years, but are more accessible today. Ab-initio methods for calculating phonons in solids are summarized. The experimental techniques of calorimetry, inelastic neutron scattering, and inelastic x-ray scattering are explained with enough detail to show the issues of using these methods for investigations of vibrational thermodynamics. The explanations extend to methods of data analysis that affect the accuracy of thermodynamic information.It is sometimes possible to identify the structural and chemical origins of the differences in vibrational entropy of materials, and the number of these assessments is growing. There has been considerable progress in our understanding of the vibrational entropy of mixing in solid solutions, compound formation from pure elements, chemical unmixing of alloys, order-disorder transformations, and martensitic transformations. Systematic trends are available for some of these phase transformations, although more examples are needed, and many results are less reliable at high temperatures. Nanostructures in materials can alter sufficiently the vibrational dynamics to affect thermodynamic stability. Internal stresses in polycrystals of anisotropic materials also contribute to the heat capacity. Lanthanides and actinides show a complex interplay of vibrational, electronic, and magnetic entropy, even at low temperatures.A "quasiharmonic model" is often used to extend the systematics of harmonic phonons to high temperatures by accounting for the effects of thermal expansion against a bulk modulus. Non-harmonic effects beyond the quasiharmonic approximation originate from the interactions of thermally-excited phonons with other phonons, or with the interactions of phonons with electronic excitations. In the classical high temperature limit, the adiabatic electron-phonon coupling can have a surprisingly large effect in metals when temperature causes significant changes in the electron density near the Fermi level. There are useful similarities in how temperature, pressure, and composition alter the conduction electron screening and the interatomic force constants. Phononphonon "anharmonic" interactions arise from those non-harmonic parts of the interatomic potential that cannot be accounted for by the quasiharmonic ...

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“…Thus, Dagens [46] calculated the phonon softening associated with a 3D VHS -the examples he gave were from superconductors Nb and (doped) Pb. These ideas were used [47] to explain the structural instability found in La under pressure.…”

Section: Van Hove Scenario Before High Tcmentioning

confidence: 99%

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

Markiewicz

1997

Journal of Physics and Chemistry of Solids

371

280

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The Van Hove singularity (VHS) provides a paradigm for the study of the role of peaks in the density of states (dos) on electronic properties. More importantly, it appears to play a major role in the physics of the high-Tc superconductors, particularly since recent photoemission studies have found that the VHS is close to the Fermi level in most of the high-Tc cuprates near the composition of optimum Tc. This paper offers a comprehensive survey of the VHS model, describing both theoretical properties and experimental evidence for the picture. Special topics discussed include a survey of the Fermi surfaces of the cuprates and related compounds, and an analysis of the reliability of the slave boson approach to correlation effects. While many properties of the cuprates can be qualitatively understood by a simple rigid-band-filling model, this is inadequate for more quantitative results, since correlation effects tend to pin the Fermi level near the VHS over an extended doping range, and can lead to a nanoscale phase separation. Furthermore, the peaks in the dos lead to competition from other instabilities, both magnetic and structural (related to charge density waves). A novel form of dynamic structural instability, involving dynamic VHS-Jahn-Teller effects has been predicted. Scattered through the literature, there is considerable experimental evidence for both nanoscale phase separation of holes, and for local, possibly dynamic, structural disorder. This review attempts to gather these results into a comprehensive database, to sort the results, and to see how they fit into the Van Hove scenario. Recent experiments on underdoped cuprates are found to provide a strong confirmation that the pseudogap is driven by a splitting of the VHS degeneracy.

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Phonon anomaly near a Fermi surface topological transition

Cited by 71 publications

References 17 publications

Pressure-induced electronic topological transition in Sb₂S₃

Pressure-induced electronic topological transition in Sb₂S₃

Vibrational thermodynamics of materials

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

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Phonon anomaly near a Fermi surface topological transition

Cited by 71 publications

References 17 publications

Pressure-induced electronic topological transition in Sb2S3

Pressure-induced electronic topological transition in Sb2S3

Vibrational thermodynamics of materials

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

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Pressure-induced electronic topological transition in Sb₂S₃

Pressure-induced electronic topological transition in Sb₂S₃