Pressure‐induced optical phonon self‐energy changes in rhenium metal

Ponosov, Yu. S.; Loa, I.; Mogilenskikh, V. E.; Bolotin, G. A.; Syassen, K.

doi:10.1002/pssc.200405366

Cited by 4 publications

(4 citation statements)

References 12 publications

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“…Anharmonic effects are usually modeled by three-and four-phonon decay processes [49][50][51] where a dominance of four-phonon processes can lead to phonon hardening and increasing lifetimes. [52][53][54] A possible explanation of this finding is that due to anharmonic effects, the phonon dispersion relation evolves with temperature. [55] A second important finding presented in Figure 3b is that the A g (6) mode of pentacene changes its PO periodicity from 180° below 80 K to 90° above 150 K. This change is reversible with temperature and indicative of a profound change in the Raman tensor elements of this vibration.…”

Section: Doi: 101002/adma201908028mentioning

confidence: 99%

“…Importantly, strong anharmonicity does not necessarily lead to mode softening and decreasing phonon lifetimes. Anharmonic effects are usually modeled by three‐ and four‐phonon decay processes where a dominance of four‐phonon processes can lead to phonon hardening and increasing lifetimes . A possible explanation of this finding is that due to anharmonic effects, the phonon dispersion relation evolves with temperature …”

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confidence: 99%

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Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

et al. 2020

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The intermolecular lattice vibrations in small‐molecule organic semiconductors have a strong impact on their functional properties. Existing models treat the lattice vibrations within the harmonic approximation. In this work, polarization‐orientation (PO) Raman measurements are used to monitor the temperature‐evolution of the symmetry of lattice vibrations in anthracene and pentacene single crystals. Combined with first‐principles calculations, it is shown that at 10 K, the lattice dynamics of the crystals are indeed harmonic. However, as the temperature is increased, specific lattice modes gradually lose their PO dependence and become more liquid‐like. This finding is indicative of a dynamic symmetry breaking of the crystal structure and shows clear evidence of the strongly anharmonic nature of these vibrations. Pentacene also shows an apparent phase transition between 80 and 150 K, indicated by a change in the vibrational symmetry of one of the lattice modes. These findings lay the groundwork for accurate predictions of the electronic properties of high‐mobility organic semiconductors at room temperature.

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Section: Doi: 101002/adma201908028mentioning

confidence: 99%

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confidence: 99%

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

et al. 2020

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“…This provides an additional tool to study the electronic excitations responsible for anomalous dispersion effects. Experiments at pressures up to 15 GPa have shown that the volume changes contribute no more than 20%-30% to the temperature-induced hardening of the phonon frequencies in osmium and rhenium, 24,25 confirming the dominant role of the e-ph interaction. [26][27][28] An anomalous phonon hardening in osmium has been found at pressures higher than 15 GPa under nonhydrostatic conditions.…”

Section: Introductionmentioning

confidence: 88%

Q-dependent electronic excitations in osmium: Pressure- and temperature-induced effects

et al. 2008

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Raman scattering by electrons and phonons has been studied in single crystals of the 5d transition-metal osmium under pressures up to 60 GPa in the temperature range of 10-300 K. An anomalous increase in the electronic light-scattering cross section was found in the pressure range of 20-30 GPa with the use of green and blue excitation wavelengths. At these conditions, we observe an appearance of well-defined electronic peaks at ϳ580 cm −1 for the wave-vector direction q ʈ ͓0001͔ and at ϳ350 cm −1 for q ʈ ͓1010͔. The comparison of q dependencies measured and calculated from the first-principles spectra suggests a strong volume-and temperature-dependent renormalization of the energies and damping of the electronic states near the Fermi level.

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“…There, the coupling is indicated by an anomalous temperature behavior of the E 2g phonon linewidths. Along with this anomaly, the phonon frequencies showed a typical softening upon cooling [17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

Raman evidence for nonadiabatic effects in optical phonon self-energies of transition metals

Ponosov

Streltsov

2016

Phys. Rev. B

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We report a Raman study of the effect of temperature on the self-energies of optical phonons in a number of transition metals with hexagonal-close-packed structure. Anisotropic softening of phonon energies and narrowing of phonon linewidths with increasing temperature are observed. These effects are reproduced in the calculations of phonon spectral functions based on ab initio electronic structures and with carrier scattering by phonons taken into account. The combined observations and results of simulations indicate a relation between observed anomalies and the renormalization of the electron spectrum due to electron-phonon interaction. It is emphasized that the temperature dependence of the phonon energies resembles anharmonic behavior but is actually an electron-induced effect.

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Pressure‐induced optical phonon self‐energy changes in rhenium metal

Cited by 4 publications

References 12 publications

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

Q-dependent electronic excitations in osmium: Pressure- and temperature-induced effects

Raman evidence for nonadiabatic effects in optical phonon self-energies of transition metals

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