Unraveling the magnetic properties and nature of exchange interactions of Mn_5-x Fe _x Ge₃ (0.15 x 0.5) alloys

We report the structural and magnetic properties of arc-melted Fe-doped Mn5Ge3 alloys. In this study, Mn5-xFexGe3 (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 beta, gamma and delta are obtained independently from different methods. For Mn4.85Fe0.15Ge3, beta = 0.338, gamma = 1.146 and delta = 4.39; for Mn4.7Fe0.3Ge3, beta = 0.337, gamma = 1.244 and delta = 4.69 and for Mn4.5Fe0.5Ge3, beta = 0.328, gamma = 1.195 and delta = 4.64. The values of critical exponents obtained are found to be close to the 3D Ising universality class (beta = 0.325, gamma = 1.241, and delta = 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 Mn5-xFexGe3 alloys.