Glass-like phonon dynamics and thermal transport in a GeTe nanocomposite at low temperature
Résumé
In this work we report the experimental evidence of glass-like phonon dynamics and thermal conductivity in a nanocomposite made
of GeTe and amorphous carbon, of interest for microelectronics, and specifically phase change memories. We show that, the total
thermal conductivity is reduced by a factor of 3 at room temperature with respect to pure GeTe, due to the reduction of both electronic
and phononic contributions. This latter, similarly to glasses, is small and weakly increasing with temperature between 100 K
and 300 K, indicating a mostly diffusive thermal transport and reaching a value of 0.86(7) Wm−1K−1 at room temperature. A thorough
investigation of the nanocomposite’s phonon dynamics reveals the appearance of an excess intensity in the low energy vibrational
density of states, reminiscent of the Boson peak in glasses. These features can be understood in terms of an enhanced phonon
scattering at the interfaces, due to the presence of elastic heterogeneities, at wavelengths in the 2-20 nm range. Our findings confirm
recent simulation results on crystalline/amorphous nanocomposites and open new perspectives in phonon and thermal engineering
through the direct manipulation of elastic heterogeneities.
Domaines
Physique [physics]| Origine | Fichiers produits par l'(les) auteur(s) |
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