ausblenden:
Schlagwörter:
Condensed Matter; Materials Science
Zusammenfassung:
Electron-phonon coupling directly determines the stability of cooperative order in solids, including
superconductivity, charge, and spin density waves. Therefore, the ability to enhance or reduce electron-phonon
coupling by optical driving may open up new possibilities to steer materials’ functionalities, potentially at high
speeds. Here, we explore the response of bilayer graphene to dynamical modulation of the lattice, achieved by
driving optically active in-plane bond stretching vibrations with femtosecond midinfrared pulses. The driven state
is studied by two different ultrafast spectroscopic techniques. First, terahertz time-domain spectroscopy reveals
that the Drude scattering rate decreases upon driving. Second, the relaxation rate of hot quasiparticles, as measured
by time- and angle-resolved photoemission spectroscopy, increases. These two independent observations are
quantitatively consistent with one another and can be explained by a transient threefold enhancement of the
electron-phonon coupling constant. The findings reported here provide useful perspective for related experiments,
which reported the enhancement of superconductivity in alkali-doped fullerites when a similar phonon mode was
driven.
