Wide-range wavevector selectivity of magnon gases in Brillouin light scattering spectroscopy

Brillouin light scattering spectroscopy is a powerful technique for the study of fast magnetization dynamics with both frequency and wavevector resolutions. Here, we report on a distinct improvement of this spectroscopic technique toward two-dimensional wide-range wavevector selectivity in a backward scattering geometry. Spin-wave wavevectors oriented perpendicularly to the bias magnetic field are investigated by tilting the sample within the magnet gap. Wavevectors which are oriented parallel to the applied magnetic field are analyzed by turning the entire setup, including the magnet system. The setup features a wide selectivity of wavevectors up to 2.04x10(5) rad/cm for both orientations, and allows selecting and measuring wavevectors of dipole- and exchange-dominated spin waves of any orientation to the magnetization simultaneously.