Details

Autor(en) / Beteiligte

• Otto, Martin R
• Pöhls, Jan-Hendrik
• René de Cotret, Laurent P
• Stern, Mark J
• Sutton, Mark
• Siwick, Bradley J

Titel

Mechanisms of electron-phonon coupling unraveled in momentum and time: The case of soft phonons in TiSe2

Ist Teil von

• Science advances, 2021-05, Vol.7 (20)

Ort / Verlag

American Association for the Advancement of Science

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Ultrafast photoexcitation of a layered quantum material yields an energy increase of a specific vibrational mode. The complex coupling between charge carriers and phonons is responsible for diverse phenomena in condensed matter. We apply ultrafast electron diffuse scattering to unravel electron-phonon coupling phenomena in 1T-TiSe 2 in both momentum and time. We are able to distinguish effects due to the real part of the many-body bare electronic susceptibility, R [ χ 0 ( q ) ] , from those due to the electron-phonon coupling vertex, g q , by following the response of semimetallic (normal-phase) 1T-TiSe 2 to the selective photo-doping of carriers into the electron pocket at the Fermi level. Quasi-impulsive and wave vector–specific renormalization of soft zone-boundary phonon frequencies (stiffening) is observed, followed by wave vector–independent electron-phonon equilibration. These results unravel the underlying mechanisms driving the phonon softening that is associated with the charge density wave transition at lower temperatures.