Coherent Phonon-Driven Band Renormalizations in 1T$'$-MoTe$_2$

TL;DR

This study uses advanced spectroscopic techniques and calculations to reveal how specific phonon modes selectively couple with electronic states in 1T'–MoTe2, leading to measurable band renormalizations.

Contribution

It introduces a combined experimental and theoretical approach to resolve ultrafast, band-specific electron-phonon interactions in a quantum material.

Findings

Distinct phonon modes couple selectively with electronic bands.

Band renormalizations of a few meV are observed.

Theoretical calculations qualitatively match experimental results.

Abstract

Here, we investigate phonon mode- and electron band-selective electron-phonon couplings in centrosymmetric 1T$'$-MoTe$_2$ using time- and angle-resolved photoemission spectroscopy combined with frequency-domain analysis. Femtosecond near-infrared pulses excite coherent $A_g$-symmetric phonon modes at 2.34 THz, 3.34 THz, and 3.86 THz, which manifest as oscillatory modulations in photoemission intensity and binding energy across the valence bands. Pixel-wise Fourier analysis using recently developed methodologies reveals pronounced band selectivity with distinct coupling strengths for different electronic states and phonon modes, enabling the evaluation of band-renormalization amplitudes in the range of few meV. Ab initio calculations qualitatively reproduce the experimentally observed coupling patterns and relative trends, demonstrating the capability of combined experimental and theoretical approaches to resolve ultrafast electron-phonon interactions in quantum materials.