Observation of the periodic and chaotic automodulations of the nonlinear magnetoacoustic vibrations in perfect FeBO3 crystal by neutron diffraction method

The native anharmonicity of acoustic waves in solids is usually small, even for big acoustic amplitudes. However, in the magnetically ordered crystals, the anharmonicity can be effectively enhanced because of the coupling of the acoustic vibrations with magnetic ones as the latter is usually much more nonlinear than the former. Especially strong are the magnetoelastic coupling and the acoustic anharmonicity in the easy plane of weak ferromagnets. The broad possibilities of the neutron diffraction method for studying the time-dependent acoustic effects in perfect weak ferromagnet crystals are demonstrated.