Directional Pumping of Coherent Phonons and Quasiparticle Renormalization in a Dirac Nodal-Line Semimetal

Identifying efficient pathways to modulate quantum coherence is a crucial step toward realizing ultrafast switching of macroscopic orders, which requires the microscopical understanding of the interplay between multidegrees of freedom. Here, we demonstrate an all-optical method to control the coherent electron and lattice excitation in a prototypical nodal-line semimetal ZrSiS. We show the displacive excitation of two coherent Raman-active phonon modes, which results in a mode-selective renormalization of its topological band structure comparable with previous experimental observations. We subsequently realize an effective manipulation of the coherent lattice vibration, not only for their amplitude, but also a <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>π</a:mi></a:math>-phase shift by tuning the laser intensity and frequency. We pinpoint that such a phase shift originates from the photoinduced carrier redistribution and can, in turn, determine the quasiparticle renormalization, for example, to induce an ultrafast topological Lifshitz transition, which we anticipate can be detected by pump-probe transport measurements. These results address the requirements for a directional pumping of coherent phonons with laser fields and provide the opportunity to explore exotic nonequilibrium physics.