Co substitution effect on magnetic properties of magnetostrictive compounds Tb0.36Dy0.64(Fe1−xCox)2 (0⩽x⩽0.30)

The substitution effect of Co for Fe on magnetic properties of giant magnetostrictive compounds Tb0.36Dy0.64(Fe1−xCox)2 (0⩽x⩽0.30) was examined by 57Fe Mössbauer measurements. It was found that the Co substitution did not change the easy magnetization direction (EMD). The average hyperfine fields and the deduced Fe moment increased with increasing Co content. The composition dependences of the magnetic transition temperatures, magnetization and magnetostrictions were consistent with the variation of hyperfine parameters, which can be ascribed to the 3d electrons transfer between Fe and Co atoms.