Magnetic properties of Y₂Fe_17−x Ga _x and Sm₂Fe_17−xGa _x compounds

Abstract

The magnetic properties of Y₂Fe_17−x Ga _x and Sm₂Fe_17−xGa _x for 3 ≤ x ≤ 7 have been investigated using the ⁵⁷Fe Mössbauer spectroscopy at room temperature. These compounds have the rhombohedral Th₂Zn₁₇ structure. X-ray diffraction analyses of aligned powders show that the easy direction of magnetization is parallel to the c-axis in Y₂Fe₁₀Ga₇ and Sm₂Fe₁₄Ga₃ and is perpendicular to the c-axis in Y₂Fe₁₄Ga₃, Y₂Fe₁₂Ga₅, Sm₂Fe₁₂Ga₅ and Sm₂Fe₁₀Ga₇. Mössbauer studies indicate that all the samples studied are ferromagnetically ordered. The ⁵⁷Fe hyperfine field decreases with increasing Ga content. This decrease results from the decreased magnetic exchange interactions resulting from Ga substitution. The average isomer shift, δ, for Y₂Fe_17−xGa _x and Sm₂Fe_17−xGa _x at room temperature is positive and the magnitude of δ increases with increasing Ga content.