According to Fourier's law, a temperature difference across a material results in a linear temperature profile and a thermal conductance that decreases inversely proportional to the system length. These are the hallmarks of diffusive heat flow. Here, we report heat flow in ultrathin (25 nm) GaP nanowires in the absence of a temperature gradient within the wire and find that the heat conductance is independent of wire length. These observations deviate from Fourier's law and are direct proof of ballistic heat flow, persisting for wire lengths up to at least 15 mu m at room temperature. When doubling the wire diameter, a remarkably sudden transition to diffusive heat flow is observed. The ballistic heat flow in the ultrathin wires can be modeled within Landauer's formalism by ballistic phonons with an extraordinarily long mean free path.

Ballistic Phonons in Ultrathin Nanowires / Vakulov, D; Gireesan, S; Swinkels, My; Chavez, R; Vogelaar, T; Torres, P; Campo, A; De Luca, M; Verheijen, Ma; Koelling, S; Gagliano, L; Haverkort, Jem; Alvarez, Fx; Bobbert, Pa; Zardo, I; Bakkers, Epam. - In: NANO LETTERS. - ISSN 1530-6984. - 20:4(2020), pp. 2703-2709.

Ballistic Phonons in Ultrathin Nanowires

De Luca, M;
2020

Abstract

According to Fourier's law, a temperature difference across a material results in a linear temperature profile and a thermal conductance that decreases inversely proportional to the system length. These are the hallmarks of diffusive heat flow. Here, we report heat flow in ultrathin (25 nm) GaP nanowires in the absence of a temperature gradient within the wire and find that the heat conductance is independent of wire length. These observations deviate from Fourier's law and are direct proof of ballistic heat flow, persisting for wire lengths up to at least 15 mu m at room temperature. When doubling the wire diameter, a remarkably sudden transition to diffusive heat flow is observed. The ballistic heat flow in the ultrathin wires can be modeled within Landauer's formalism by ballistic phonons with an extraordinarily long mean free path.
2020
Nanowires; GaP; heat transport; ballistic phonons; Raman spectroscopy
01 Pubblicazione su rivista::01a Articolo in rivista
Ballistic Phonons in Ultrathin Nanowires / Vakulov, D; Gireesan, S; Swinkels, My; Chavez, R; Vogelaar, T; Torres, P; Campo, A; De Luca, M; Verheijen, Ma; Koelling, S; Gagliano, L; Haverkort, Jem; Alvarez, Fx; Bobbert, Pa; Zardo, I; Bakkers, Epam. - In: NANO LETTERS. - ISSN 1530-6984. - 20:4(2020), pp. 2703-2709.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1558044
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