Critical Behavior at Paramagnetic to Ferromagnetic Phase Transition in MnFeGe Compound

Abstract

The critical behavior of MnFeGe polycrystalline compound was studied by dc magnetization measurement around the Curie temperature (T C ). A set of critical exponents (β, γ, δ) is achieved by the modified Arrott plot technique, Kouvel–Fisher method, and critical isothermal analysis. With these obtained exponents, the magnetization-field-temperature curves collapse into two independent curves following a single scaling equation M|t|−β = f ±(H|t|−(β+γ)) around T C , suggesting the reliability of the obtained exponents. But this set of exponents does not belong to any classical theoretical models, e.g., mean-field model, three-dimensional (3D) Heisenberg model and 3D Ising model. It is suggested that the coexistence of the localized 3d magnetic interaction and itinerant Fe-Ge hybridization should be responsible for the critical behavior in this compound.