Electron cooling in graphene enhanced by plasmon-hydron resonance
Abstract
Evidence is accumulating for the crucial role of a solid's free electrons in the dynamics of solid-liquid interfaces. Liquids induce electronic polarization and drive electric currents as they flow; electronic excitations, in turn, participate in hydrodynamic friction. Yet, the underlying solid-liquid interactions have been lacking a direct experimental probe. Here, we study the energy transfer across liquid-graphene interfaces using ultrafast spectroscopy. The graphene electrons are heated up quasi-instantaneously by a visible excitation pulse, and the time evolution of the electronic temperature is then monitored with a terahertz pulse. We observe that water accelerates the cooling of the graphene electrons, whereas other polar liquids leave the cooling dynamics largely unaffected. A quantum theory of solid-liquid heat transfer accounts for the water-specific cooling enhancement through a resonance between the graphene surface plasmon mode and the so-called hydrons -- water charge fluctuations --, particularly the water libration modes, that allows for efficient energy transfer. Our results provide direct experimental evidence of a solid-liquid interaction mediated by collective modes and support the theoretically proposed mechanism for quantum friction. They further reveal a particularly large thermal boundary conductance for the water-graphene interface and suggest strategies for enhancing the thermal conductivity in graphene-based nanostructures.
Keywords
Cite
@article{arxiv.2301.05095,
title = {Electron cooling in graphene enhanced by plasmon-hydron resonance},
author = {Xiaoqing Yu and Alessandro Principi and Klaas-Jan Tielrooij and Mischa Bonn and Nikita Kavokine},
journal= {arXiv preprint arXiv:2301.05095},
year = {2023}
}