Giant modulation of second harmonic generation in MnPS₃ by Floquet engineering

Floquet engineering provides a promising pathway to coherently tune the electrical, magnetic and optical properties of materials using periodic driving with light. However, runaway heating due to the strong requisite field strengths is a major impediment to experimental progress. In my talk, I will demonstrate that by driving the van der Waals insulator MnPS₃ below its charge gap, large peak electric fields (up to 10⁹ V/m) can be imparted without any measurable heat dissipation. Using high-field time-resolved second harmonic generation (SHG) spectroscopy and polarimetry, I will show evidence of a large coherent band gap widening effect, enabling a coherent modulation of the optical nonlinearity of MnPS₃ with an on-to-off ratio exceeding 10. These observations are quantitatively reproduced using a single-ion based Floquet theoretic model.