Mandelstam‐Brillouin scattering of light in antiferromagnets (invited)

The report reviews experimental investigations on Mandelstam‐Brillouin light scattering (MBS) from thermal and excited low energy (1–3 cm−1) quasiparticles (magnons and phonons) in antiferromagnets. Now such investigations have been performed in two rhombohedral antiferromagnets with weak ferromagnetism, FeBO3 and CoCO3. The spin wave spectrum of these substances has a low frequency branch. The MBS experiments allowed to distinguish the contributions in magnon energy from exchange, magnetic, and magnetodipole interactions. Spin wave velocities along trigonal axis and in basal plane of crystals were determined. The second part of the report is devoted to the results of optical experiments on investigation of relaxation processes of magnons with k∼0, excited by antiferromagnetic resonance. The overheating of magnon’s and phonon’s systems in crystal, caused by the so‐called ’’bottle neck’’ during relaxation, was discovered. The observation experiments on MBS on parametrically excited magnons and phonons are ...