Controlling nanoscale heat transfer is crucial to design next-generation electronic devices as
heat management becomes a bottleneck to increase their efficiency. Phonon engineering leads
to a controlled modification of phonon dispersion, phonon interactions, and transport [1,2].
However, engineering and probing phonons and phonon transport at the nanoscale is a non-
trivial problem.

We have built a powerful toolbox of noncontact pump-probe techniques, that combines
frequency-domain thermoreflectance, time-resolved Raman spectroscopy and transient
reflectivity. We applied these techniques to various material systems, showing diverse
mechanisms responsible for the energy flow after laser excitation, critical to understand heat
dissipation in miniaturized devices [3]. These results shed light on the intricate interplay
between lattice dynamics and thermal transport phenomena, and prove that the combination
of these techniques is an effective approach to investigate materials for efficient next-
generation electronic devices.

We will also discuss how phononic properties and thermal transport can be engineered and
measured in nanostructures and the challenges and progresses in the measurement of the
thermal conductivity of nanostructures and low dimensional systems. The concept of phonon
engineering in nanowires is exploited in GaAs/GaP superlattice nanowires [4,5]. We
experimentally show that a controlled design of the nanowires’ phononic properties can be
decided à la carte by tuning the superlattice period.

[1] M. Maldovan, Nature 503, 209 (2013).
[2] S. Voltz, J. Ordonez-Miranda, et al. Eur. Phys. J. B 89, 15 (2016).
[3] G. Raciti, B. Abad, et al. Advanced Science, in press (2025). DOI: 10.1002/advs.202515470
[4] A. K. Sivan, B. Abad, et al. ACS Appl. Nano Mater. 6 (19), 18602-18613 (2023)
[5] C. Arya, J. Trautvetter, et al. ACS Nano, in press (2025). DOI: 10.1021/acsnano.5c10312