Phys.org  November 10, 2021 Researchers in China developed a highly efficient magneto-tunable and phonon-based monochromatic THz generator with a frequency of ~0.9 THz using a 2D ferromagnetic Cr2Ge2Te6 crystal. They combined theoretical and experimental approaches and innovatively exploited the excellent properties of its van der Waals interlayered breathing phonon mode (boson) with THz-TDS (time domain spectroscopy) magneto-optic system. They found the breathing mode could effectively couple with incident co-frequency THz pulse and form a phonon-polariton. This quasi-bosonic particle could then generate far-field electro-magnetic radiation with monochromatic frequency comparable to the phonon mode. They regulated the radiation via the spin-phonon interaction […]