Mechanisms of electron-phonon coupling unraveled in momentum and time: The case of soft phonons in TiSe<sub>2</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33980488.
- Also identified by DOI 10.1126/sciadv.abf2810 and PMC identifier 8115930.
- Licence recorded as CC BY-NC.
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Abstract
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<sub>2</sub> in both momentum and time. We are able to distinguish effects due to the real part of the many-body bare electronic susceptibility, [Formula: see text], from those due to the electron-phonon coupling vertex, <i>g</i> <sub><b>q</b></sub> , by following the response of semimetallic (normal-phase) 1T-TiSe<sub>2</sub> 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.