Magnetic structure of Gd-Y single-crystal alloys from neutron diffraction and magnetization measurements

Abstract

The first neutron-diffraction study of the helical phase of Gd-Y alloys in the vicinity of 30 at.% Y is presented. For each alloy composition the turn angle of the helix is seen to go smoothly to zero at the phase boundary with the low-temperature canted-ferromagnetic phase. The initial (onset) turn angle decreases rapidly with increasing Gd concentration, tending to zero at \ensuremath{\sim}29.7 at.% Y. Combining the neutron data with magnetization, resistivity, and ultrasonic data allows us to construct a definitive magnetic phase diagram for the Gd-Y system. Two multicritical points are observed but neither complies fully with all the conditions necessary for a Lifshitz point.