Direct determination of mode-projected electron-phonon coupling in the time domain

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Ultrafast Spectroscopy

Background:

• Ultrafast spectroscopies are crucial for understanding quantum material dynamics.
• Tracking nonthermal electron behavior reveals dominant scattering processes.
• Electron-phonon coupling significantly influences material properties.

Purpose of the Study:

• To present a novel time-domain method for quantifying electron-phonon coupling strength.
• To demonstrate this method using time- and angle-resolved photoemission spectroscopy (TR-ARPES).
• To extract quantitative electron-phonon matrix elements for specific phonon modes.

Main Methods:

• Utilizing time- and angle-resolved photoemission spectroscopy (TR-ARPES).
• Investigating photoinjected electron dynamics in graphite at the K point.
• Analyzing quantized energy-loss processes attributed to optical phonon emission.

Main Results:

• Successfully demonstrated a method for extracting electron-phonon coupling strength in the time domain.
• Observed quantized energy-loss events corresponding to strongly coupled optical phonons in graphite.
• Determined the characteristic time scale for spectral weight transfer due to phonon scattering.

Conclusions:

• The developed TR-ARPES method enables direct, quantitative extraction of electron-phonon matrix elements.
• This technique provides insights into specific phonon modes and their coupling strengths.
• The findings advance the understanding of electron dynamics and scattering in quantum materials.