Begoña Abad
Department of Physics, University of Basel


Ultrafast coherent beams illuminate understanding of phonon transport


Phonons—vibrations of the atomic lattice—are responsible for sound and heat propagation, and behave radically differently in nanostructured systems. Controlling phonons is key for engineering thermal properties, critical to energy-efficient nano-electronics, thermoelectric devices, photovoltaics, and sensors. However, measuring thermal transport at the nanoscale is especially difficult due to small, localized temperature gradients as well as significant thermal contact resistances. Therefore, new experimental tools are needed in order to explore new regimes of nanoscale phonon transport. Non-contact coherent light-based metrology techniques are a very powerful approach used to nondestructively access new behaviors. Here, I will present advances in the understanding of non-diffusive heat flow away from nanoscale heat sources probed by extreme ultraviolet coherent beams. In particular, we experimentally showed that nanoscale heat sources placed together dissipate heat more efficiently than when they are further away [1]. Additionally, I will present recent efforts in the development of a multi-measurement versatile technique based on transient reflectivity and time-resolved Raman spectroscopy to characterize carrier and lattice dynamics as well as different regimes of thermal transport.
[1] Beardo, J. L. Knobloch, L. Sendra, J. Bafaluy, T. D. Frazer, W. Chao, J. N. Hernandez-Charpak, H. C. Kapteyn, B. Abad, M. M. Murnane, F. X. Alvarez, and J. Camacho. “A General and Predictive Understanding of Thermal Transport from 1D- and 2D-Confined Nanostructures: Theory and Experiment”. ACS Nano, 2021, 15 (8), 13019-13030.


Begoña Abad carried out her PhD in Physics at the Institute of Micro and Nanotechnology (IMN-CSIC, Spain). Her thesis work focused on the development of thermal property measurement techniques to characterize the efficiency of thermoelectric materials. In 2016 she moved to the University of Colorado Boulder (USA) where she joined the Kapteyn-Murnane group at JILA. She used coherent extreme ultraviolet light to uncover phonon and acoustic dynamics of nanoscale materials. She was awarded with a Marie S?owdoska Curie fellowship in the Nanophononics group in the Department of Physics of University of Basel where she combines ultrafast spectroscopies to explore carrier dynamics and different regimes of phonon transport in nanoscale systems.