Terahertz displacive excitation of a coherent Raman-active phonon in V2O3

Nonlinear processes involving frequency-mixing of light fields set the basis for ultrafast coherent spectroscopy of collective modes in solids. In certain semimetals and semiconductors, generation of coherent phonon modes can occur by a displacive force on the lattice at the difference-frequency mixing of a laser pulse excitation on the electronic system. Here, as a low-frequency counterpart of this process, we demonstrate that coherent phonon excitations can be induced by the sum-frequency components of an intense terahertz light field, coupled to intraband electronic transitions. This nonlinear process leads to charge-coupled coherent dynamics of Raman-active phonon modes in the strongly correlated metal V2O3. Our results show an alternative up-conversion pathway for the optical control of Raman-active modes in solids mediated by terahertz-driven electronic excitation. The use of intense light to control transient properties of quantum materials is a subject of current interest in ultrafast condensed matter physics. Here, a new up-conversion pathway for the optical control of Raman-active modes is demonstrated via a terahertz field-driven nonlinear process in the strongly-correlated metal, V2O3.

Automated summary

This study demonstrates a new pathway for optically controlling Raman-active modes in a strongly-correlated metal through a terahertz field-driven nonlinear process.