Low field magnetic studies of some alloys

Abstract

Polycrystalline pure Gd and Gd 1−x La x (x = 0.15, 0.25, 0.27 and 0.50) alloys have been studied by low field magnetic susceptibility (χ AC ), magnetization and electrical resistivity measurements. Measurements were also performed on samples with low demagnetizing factor geometry in order to study the ground state properties of these systems. For hexagonal closepacked (hcp) samples the effect of spin reorientation is indicated by a broad peak in the susceptibility curve and it shifts rapidly to lower temperatures with increasing La content in Gd metal. The spin reorientation effect is not observed in the samples with La concentration higher than 15%. The χ AC and resistivity measurements indicate a ferromagnetic transition at T C = 225 K for 15% La concentration. For the Sm-type structure sample, with x = 0.27, two magnetic transition peaks are observed at 135 K and 113 K and helical antiferromagnetic order is suggested. Finally, the results for the x = 0.50 alloy with double hexagonal close-packed (dhcp) crystalline structure indicate a spin-glass magnetic phase type, below T g = 30 K. Observed magnetization remanent effects, in this latter case, give additional support for the presence of the spin-glass phase.

Anomalous slow dynamics in the metallic helimagnet Gd1−xYx

“…Therefore, we conclude that the randomness due to the dilution is not the origin of the slow dynamics and nonlinearity of the magnetization in Gd 1−x Y x . It should be noted that similar nonlinearity has been reported in Gd 1−x La x in a previous work [10]. The previous and our experimental results suggest that these anomalous behaviors result from the weak magnetic anisotropy of Gdmoment.…”