Magnetic transitions and magnetostrictive properties ofTbxDy1−x(Fe0.8

Abstract

The magnetic transitions and magnetic and magnetostrictive properties of Tb x Dy 1−x ͑Fe 0.8 Co 0.2 ͒ 2 ͑0.20ഛ x ഛ 0.40͒ compounds have been investigated. The spin-reorientation temperature T SR decreases from above to below room temperature, when x is increased from 0.25 to 0.40. The easy magnetization direction at room temperature of the Laves phase lies along the ͗100͘ axis in compounds with 0.20ഛ x ഛ 0.27, while it lies along the ͗111͘ axis as 0.30ഛ x ഛ 0.40. The magnetocrystalline anisotropy constant K 1 at room temperature reaches a minimum value at x = 0.30, indicating it is near the composition for anisotropy compensation. The large polycrystalline saturation magnetostriction s Ϸ 980 ppm is observed for x = 0.30, which can be ascribed to the large magnetostriction coefficients 111 and 100 . 100 has a value larger than 600 ppm for the compounds with 0.30ഛ x ഛ 0.35, which can be attributed to the change of the filling of the 3d band due to Co substitution for Fe. Tb 0.30 Dy 0.70 ͑Fe 0.8 Co 0.2 ͒ 2 with a high magnetostriction and a low anisotropy is found to be a good candidate material for magnetostriction applications. A detailed spin configuration diagram for Tb x Dy 1−x ͑Fe 0.8 Co 0.2 ͒ 2 Laves phase around the composition for the anisotropy compensation is given, which should be a guide to develop novel magnetostrictive materials for applications in this series.

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