Direct Observation of Gigahertz Coherent Guided Acoustic Phonons in Free-Standing Single Copper Nanowires.
We report on gigahertz acoustic phonon waveguiding in free-standing single copper nanowires studied by femtosecond transient reflectivity measurements. The results are discussed on the basis of the semianalytical resolution of the Pochhammer and Chree equation. The spreading of the generated Gaussian wave packet of two different modes is derived analytically and compared with the observed oscillations of the sample reflectivity. These experiments provide a unique way to independently obtain geometrical and material characterization. This direct observation of coherent guided acoustic phonons in a single nano-object is also the first step toward nanolateral size acoustic transducer and comprehensive studies of the thermal properties of nanowires.
†Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.|‡CNRS, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.
Cyril
C
Jean
†Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.|‡CNRS, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.
Laurent
L
Belliard
¶Aix-Marseille Université, CNRS UMR 7334, IM2NP, F-13397 Marseille Cedex, France.
Thomas W
TW
Cornelius
¶Aix-Marseille Université, CNRS UMR 7334, IM2NP, F-13397 Marseille Cedex, France.
Olivier
O
Thomas
§GSI Helmholtz Centre for Heavy Ion Research, D-64291 Darmstadt, Germany.
Maria Eugenia
ME
Toimil-Molares
§GSI Helmholtz Centre for Heavy Ion Research, D-64291 Darmstadt, Germany.
Marco
M
Cassinelli
†Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.|‡CNRS, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.
Loïc
L
Becerra
†Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.|‡CNRS, UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.
Bernard
B
Perrin
acoustic waveguide; asoustic vibration in nano-object; copper nanowire; guided phonons; time-resolved spectroscopy