Structure, Magnetic, and Electrical Properties of Heusler-Type Fe3-x Co x Si Ferromagnetic Alloys

The effect of substitution of Co for Fe on structure, magnetic, and electrical resistivity of Heusler-type Fe3-x Co (x) Si (0 a parts per thousand currency sign x a parts per thousand currency sign 1) alloys was investigated using X-ray powder diffraction, Fe-57 Mossbauer spectroscopy, magnetic, and electrical transport measurements. The results revealed that these alloys consist of ordered DO3 phase and some L2(1) phase up to x a parts per thousand currency sign 0.5. However, for x > 0.5, the alloys consisted of L2(1) ordered phase and B2 disordered phase. The magnetization value was close to that predicted from Slater-Pauling rule for x a parts per thousand yen 0.5 alloys. The Curie temperature increased from 832 K (559 A degrees C) for x = 0 (Fe3Si) alloy to 1016 K (743 A degrees C) for x = 1 (Fe2CoSi) alloy. Electrical transport studies revealed the presence of half-metallic behavior at low temperatures in x a parts per thousand yen 0.5 alloys. No half-metallic behavior was observed for x = 0 and 0.25 alloys; however, a high resistivity with ferromagnetism was observed in these alloys, which is desirable for ferromagnetic metal/semiconductor spintronic devices.