Temperature and magnetic field dependences of ultrasonic behaviors in ferromagnetic Sm1−xGdxAl2 (x = 0, 0.01) intermetallics

The temperature and magnetic field dependences of ultrasonic parameters have been studied on polycrystalline Sm1−xGdxAl2 (x = 0, 0.01). Considerable change of ultrasonic parameters in the ordered state can be suppressed efficiently by the applied field and associated with domains and magnetic fluctuation. Ultrasonic anomalies observed near the magnetic compensation temperature in the Gd-doped sample are related to the sign reversal of magnetic moments. We suggest that the splitting of the attenuation peak and velocity minimum under the fields results from the weaker influence of the field on the realignment of the magnetic moments while approaching the compensation point.