Photoinduced Interlayer Dynamics in T\(_d\)-MoTe\(_2\): A Broadband Pump-Probe Study

We report on time-resolved broadband transient reflectivity (tr-bb-TR) measurements performed on a bulk single crystal of T\(_d\)-MoTe\(_2\) as a function of the incident pump fluence (F). Tr-bb-TR data unveil photoinduced electronic changes progressing on the sub-picosecond timescale as well as the dynamics of the coherent low-frequency \(^1A_1\) interlayer shear phonon. Our results indicate a gradual evolution of both the TR and the \(^1A_1\) Fourier intensity spectra as a function of F, ruling out the threshold-like change that has been associated with the ultrafast photoinduced \(T_d \to 1T'\) phase transition. We also observe a large redshift of the \(^1A_1\) Fourier spectral features, which suggests that large renormalization effects are taking place on interband transitions that are dielectrically susceptible to the \(^1A_1\) interlayer phonon displacement.