Determining the Eutectic Compositions in the Ga-Sm and Ga-Yb Systems via Magnetic Measurements

Dilute rare earth alloys containing mixed-valence elements are of particular interest as model systems. These materials demonstrate non-trivial structure and properties, especially in the vicinity of their eutectic compositions. When considering high-temperature electron transport and magnetism in systems of this type, it is necessary to accurately determine the eutectic points for a correct description of the observed electronic effects. Here we address these issues by the example of a series of diluted gallium alloys doped with ytterbium and samarium. To do that, we synthesize and measure magnetic susceptibilities of the diluted Ga-Sm and Ga-Yb alloys near their melting points. The results reveal that the susceptibility–temperature dependencies for the samples are very similar to that of pure gallium, while the concentration dependencies extracted from the magnetic data have nonlinear behavior for both liquid and solid states. The eutectic compositions in both investigated systems demonstrate a strong supercooling effect during continuous thermal cycling. Thermal analysis results confirm a one-stage melting for these compositions and a two-stage one for other alloys. Analysis of the obtained thermal and magnetic data allows us to accurately detect the eutectic points in both metallic systems considered. The anomalies in the magnetic properties observed for the eutectic alloys are interpreted by microstructural peculiarities typical for this type of metallic materials.