Weak magnetic field effect on the acoustic properties of terbium in the vicinity of magnetic phase transitions

Acoustic properties (velocity, attention, nonlinear acoustic parameter) of rare-earth metal of terbium (Tb) (longitudinal waves in the direction of hexagonal axis C of a crystal) at different values of an external magnetic field were investigated at 220-240 K. Considerable anomalies of acoustic Tb properties were observed in the areas of the Neel point (approximately 213 K) and the Kurie point (approximately 228 K). Dependences of attenuation and nonlinear acoustic parameter of Tb are quite different for the cases of measurements on specimen cooling and heating. The absolute value of the nonlinear parameter in the region of transition from a paraphase to antiferrophase is higher by an order, approximately, as compared with most metals