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It has been well-known that Raman and infrared linewidths are associated with third-order lattice anharmonicity. Here, the authors go further and establish by means of first-principles calculations and Raman measurements… Click to show full abstract
It has been well-known that Raman and infrared linewidths are associated with third-order lattice anharmonicity. Here, the authors go further and establish by means of first-principles calculations and Raman measurements that the previously neglected fourth-order anharmonicity may play a significant, or even dominating, role. The predicted strong fourth-order lattice anharmonicity results from the large four-phonon scattering phase space of zone-center optical phonons. It explains well the significantly broadened Raman or infrared peaks, observed for a wide range of materials at various temperatures. This finding may significantly impact spectroscopy techniques and the understanding of radiative transport.
Journal Title: Physical Review B
Year Published: 2020
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