Fig. 3: Fingerprints of the magnon-phonon Fermi resonance.
From: Magnon-phonon Fermi resonance in antiferromagnetic CoF2
a Fourier transformation of the time domain signals in Fig. 2b plotted with equidistant offset in the vicinity of the magnon (left) and phonon (right) resonance frequencies. To compensate for the THz power change of the TELBE source, magnon (phonon) spectral amplitudes are normalized by the square root of THz power (the THz power). b Phonon spectral weight (blue spheres) extracted as an integral value from the shaded frequency interval in (a). The phonon weight from our numerical calculation is shown as solid blue line. The vertical dotted line emphasizes the drop in the phonon spectral weight at Hext = 3.5 T for both simulation and experiment. Excluding effects which can additionally contribute to our signal on the time scale of our THz pump pulse, i.e., nonlinear electro-optical Kerr effect, we demonstrate even better agreement of experiment and simulation in Supplementary Section A.
