Random field effects and breakup of helimagnetism in Gd 60Y 60

Abstract

A neutron diffraction study of a single-crystal Gd 60Y 40 alloy has revealed a severe broadening of the coherent helimagnetic satellite peak widths below 60 K, indicating a decrease in the coherence length of the helimagnetic structure along the hexagonal c-axis. The peak broadening does not have the Lorentzian squared lineshape characteristic of random field effects. We suggest that this feature may be explained in part simply by the gradient of the helix-ferro II phase line in Gd-Y alloys.