Femtosecond modulation of electron correlations in a Luttinger liquid.
Journal Article
Overview
abstract
Luttinger liquids emerge in one-dimensional metals with strong electron interactions, exhibiting intriguing near-equilibrium properties such as spin-charge separation and power-law correlations. Although these interactions suggest fast, distinctive out-of-equilibrium dynamics, such phenomena remain largely unexplored on ultrashort timescales. Here, we use femtosecond laser excitation to weakly deplete the electron density in the Luttinger band of Li0.9Mo6O17 and track the response via time- and angle-resolved photoemission spectroscopy. By fitting the measured electron distributions to a finite-temperature Luttinger liquid model, we observe a fast drop in the Luttinger exponent, quantifying the strength of electron interactions. Subsequently, unlike hot electrons in conventional Fermi liquids that slowly relax within picoseconds via electron-phonon coupling, hot electrons in Li0.9Mo6O17 relax within a short time of ~100 femtoseconds, through the excitation of a nonequilibrium collective plasmon. The extremely fast evolution of the Luttinger exponent and electron temperature-including a tens of femtosecond time lag between excitation, recovery, and plasmon-driven modulation-reveals previously unidentified pathways for modulating quantum many-body interactions in low-dimensional materials.
