Dynamics of an order parameter coupled phonon in an excitonic insulator

An impulsively stimulated Raman active phonon can be suppressed or amplified using two optical pulses tailored to be period-matched with this certain mode. Ta₂NiSe₅ is an excitonic insulator candidate which exhibits multiple coherent phonons in transient reflectivity. We conducted double-pump coherent phonon spectroscopy measurements on Ta₂NiSe₅ to understand the interaction between the phonon and the excitonic order parameter. We further developed theoretical methods to simulate the dynamics of the order parameter coupled phonon.