Electromagnetic excitation of ultrasound in gadolinium

Electromagnetic excitation of ultrasound in gadolinium single crystals is studied experimentally and theoretically. The main mechanisms of electromagnetic-acoustic transformation are found, and the regions in which they are most pronounced are determined. The generation of ultrasound in a broad range of variation of the magnetic field strength and temperature occurs 1) at the expense of the para-process (near Tc), 2) as a result of spin flip (for T<Tc) and 3) in strong magnetic fields at the expense of inductive interaction. An analysis of the temperature and field dependences of the efficiency of longitudinal ultrasound generation yields the boundaries of the magnetic phases in gadolinium