ANTIFERROMAGNETISM OF METASTABLE CR-RICH CR-GD ALLOYS

Cr is an antiferromagnet with a Neel temperature of 311 K. The addition of impurities will alter the antiferromagnetic properties of materials. Studies of the effect of magnetic Gd atoms on the Cr-rich CrxGd1-x alloys are reported. The metastable CrxGd1-x alloy films (1.00 greater-than-or-equal-to x greater-than-or-equal-to 0.96) have been prepared by the rapid-quenching method. It has been found from x-ray diffraction that the alloy films with 1.00 greater-than-or-equal-to x greater-than-or-equal-to 0.97 have body-centered-cubic structure, the same as Cr. For higher Gd concentration, the alloy film contains both body-centered cubic and amorphous phases. The variation of the Neel temperature T(N) as well as the spin-flip temperature T(F) of metastable Cr-Gd alloys has been investigated by resistiviity measurements between 10 and 300 K. It has been found that T(N) decreases slowly from 311 K for pure Cr to about 290 K for Cr0.97Gd0.03. These results seem to indicate that magnetic Gd atoms show little effect on the antiferromagnetism of Cr. Furthermore, there is a broad resistivity minimum at low temperatures. This broad minimum occurs at higher temperature as Gd concentration is increasing. Thus, it suggests that a different mechanism accounts for this resistivity minimum. A detailed discussion is reported.