Magnetoelastic interaction and acoustic nonreciprocity in Gd Ni 2 B 2 C

Ultrasonic investigations of a gadolinium borocarbide single crystal have been performed. It has been found that the acoustic characteristics are highly sensitive to magnetic phase transformations. This sensitivity is due to the interaction of sound waves with the antiferromagnetic domain structure. Acoustic “nonreciprocity” of the same nature has also been observed. Arguments for the existence of weak ferromagnetism in Gd Ni 2 B 2 C are presented.