HIGH-FIELD MAGNETOSTRICTION BY THE INTERFERENCE METHOD USING AN OPTICAL-FIBER

Magnetostriction measurements in pulsed high magnetic fields at low te mperatures have been done by the interference method using an optical fiber. He-Ne laser light is introduced by a polarization fiber to a sm all mirror adhered to the sample of length l. The length change DELTAl under the field is estimated by counting the change of the interferen ce. This method has maximum sensitivity of detecting DELTAl = 5 nm. Th e new method is applied to the magnetostriction study of DyAg, a typic al material of the quadrupole-ordered antiferromagnet, and large chang es in the magnetostriction are found when the zero-field quadrupole or der is destructed under a high magnetic field.