Phonon Lifetimes throughout the Brillouin Zone at Elevated Temperatures from Experiment andAb Initio

Abstract

We obtain phonon lifetimes in aluminium by inelastic neutron scattering experiments, by ab initio molecular dynamics, and by perturbation theory. At elevated temperatures significant discrepancies are found between experiment and perturbation theory, which disappear when using molecular dynamics due to the inclusion of full anharmonicity and the correct treatment of the multiphonon background. We show that multiple-site interactions are small and that local pairwise anharmonicity dominates phonon-phonon interactions, which permits an efficient computation of phonon lifetimes.

Nonperturbative phonon scatterings and the two-channel thermal transport in Tl3VSe4

“…Additionally, different from PT, in which we only consider the third-and fourth-order terms, the machine learning GAP potential for MD simulations takes into account 224307-4 full anharmonicity up to any arbitrary orders. The deficiency of PT in predicting the phonon lifetimes of strongly anharmonic systems at high temperatures due to the absence of high-order perturbative terms has been pointed out in previous studies [33,55,56]. Artús et al also claimed that fifth-order phonon scatterings are crucial for understanding the experimental results of the transverse optical phonon properties in InP [57].…”

Generalized decay law for particlelike and wavelike thermal phonons

“…However, state-of-the-art theories are failing in simultaneously capturing both wave and particle pictures [1,2,11]. Alternative methods still miss a direct representation of thermal phonon excitations [12][13][14][15], which is the case when determining phonon lifetimes from anharmonic lattice dynamics [16][17][18] and in experimental measurements [19,20]. Recently, several groups [21,22] proposed models to consider the coherence between different thermal phonon modes, and significant effects on thermal transport are observed in glasses or complex crystals; however, the intrinsic coherence or wavelike behavior of thermal phonons still could not be revealed.…”

Theoretical investigation of decoherence channels in athermal phonon sensors

“…We are also assuming that the calculated phonon lifetimes represent a reasonable approximation to the actual scattering rate in a real material. Prior work comparing phonon lifetimes observed from Raman and inelastic neutron scattering experiments with DFT calculations show that the agreement is very reasonable as long as the temperature is small compared to the phonon frequency 66,67 . The temperature of the detector in a sensor experiment is 10 − 100 mK (equivalent to 1-10 µeV), which is much smaller than the phonon energies that we calculate.…”