Extended Data Fig. 6: Mode spectra measured at 90K and 10K with a wider temporal window.
From: Terahertz field-induced metastable magnetization near criticality in FePS3
Spectra of collective excitations as measured in the polarization rotation (a) and ellipticity change (b) channels at 90K. The detection scheme in these two channels use half waveplate (HWP) and quarter waveplate (QWP), respectively. The relative amplitudes of the modes in the energy window between 2 THz to 5 THz, are more pronounced in the polarization rotation channel. c. A time trace of THz-induced ellipticity change signal with a longer temporal window. d. Fourier transform of the oscillations in a. Owing to the longer time window, the frequency resolution is enhanced, which enabled to resolve the splitting of the two magnon energies by ~ 0.033 THz = 0.13 meV. Additionally, in this set of measurements, we can observe the mode at 2.83 THz.
