Unraveling the magnetic properties and nature of exchange interactions of Mn5−x Fe x Ge3 (0.15 ≤ x ≤ 0.5) alloys

Abstract We report the structural and magnetic properties of arc-melted Fe-doped Mn 5 Ge 3 alloys. In this study, Mn 5− x Fe x Ge 3 (x = 0.15, 0.3, and 0.5) alloys were subjected to DC magnetic measurements in order to examine the nature of magnetic interaction via critical exponents study in the asymptotic critical region. The critical exponents β , γ and δ are obtained independently from different methods. For Mn 4.85 Fe 0.15 Ge 3 , β = 0.338, γ = 1.146 and δ = 4.39; for Mn 4.7 Fe 0.3 Ge 3 , β = 0.337, γ = 1.244 and δ = 4.69 and for Mn 4.5 Fe 0.5 Ge 3 , β = 0.328, γ = 1.195 and δ = 4.64. The values of critical exponents obtained are found to be close to the 3D Ising universality class ( β = 0.325, γ = 1.241, and δ = 4.82). Analyses based on the Renormalization group theory predictions reveal that the spin interactions are short-range extended types beyond the nearest neighbors due to the presence of a different set of Mn–Mn interactions with an unequal magnitude of exchange strengths in the Mn 5− x Fe x Ge 3 alloys.