HIGH-FIELD MAGNETOSTRICTION OF TBCU, DYCU, AND HOCU

Preliminary results are presented on the anisotropic and volume magnetostriction in pulsed high magnetic fields (0-16.6 T) of the antiferromagnetic intermetallics TbCu, DyCu, and HoCu from room temperature to 5 K. The results clearly point out the relevance of these measurements in order to determine magnetic phase transitions induced by the magnetic field. The strain measured was surprisingly large, up to 10-3 for DyCu, which is the largest magnetostriction observed in an antiferromagnet. For TbCu below≊40 K, two distinct field-induced spin-reorientation transitions are exhibited at critical fields of HC1≊2 T and HC2≊8. 5 T. This result casts doubt on the collinear nature of the magnetic structure of TbCu. From 50 to 5 K the DyCu results show two anomalies at critical fields HC1≊7.5 T and HC2≊11 T. In addition, these measurements show that at 11 K and below a small anomaly occurs at H C3≊2.5 T. HoCu exhibits a complex magnetostriction behavior, but it too presents definite anomalies at HC1≊2.5 T, H C2≊9 T, and HC3≊13 T. These results would point to a noncollinear magnetic structure for HoCu. All of the critical magnetic field values observed were practically temperature independent.