Direct Measurement of Ballistic and Diffusive Electron Transport in Gold.

Karna, Pravin; Hoque, Md Shafkat Bin; Thakur, Sandip; Hopkins, Patrick E; Giri, Ashutosh · Nano Lett · 2023

basic_science · Level V

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Abstract

We experimentally show that the ballistic length of hot electrons in laser-heated gold films can exceed ∼150 nm, which is ∼50% greater than the previously reported value of 100 nm inferred from pump-probe experiments. We also find that the mean free path of electrons at the peak temperature following interband excitation can reach upward of ∼45 nm, which is higher than the average value of 30 nm predicted from our parameter-free density functional perturbation theory. Our first-principles calculations of electron-phonon coupling reveal that the increase in the mean free path due to interband excitation is a consequence of drastically reduced electron-phonon coupling from lattice stiffening, thus providing the microscopic understanding of our experimental findings.