Abstract
We report a comprehensive investigation of MnNi(0.7)Fe(0.3)Ge Heusler alloy to explore its magnetic, caloric, and electrical transport properties. The alloy undergoes a ferromagnetic transition across T (C) ∼ 212 K and a weak-antiferromagnetic transition across T (t) ∼ 180 K followed by a spin-glass transition below T (f) ∼ 51.85 K. A second-order phase transition across T (C) with mixed short and long-range magnetic interactions is confirmed through the critical exponent study and universal scaling of magnetic entropy and magnetoresistance. A weak first-order phase transition is evident across T (t) from magnetization and specific heat data. The frequency dependent cusp in χ(AC)(T) along with the absence of a clear magnetic transition in specific heat C(T) and resistivity ρ(T) establish the spin glass behavior below T (f). Mixed ferromagnetic and antiferromagnetic interactions with dominant ferromagnetic coupling, as revealed by density functional calculations, are experimentally evident from the large positive Weiss temperature, magnetic saturation, and negative magnetic-entropy and magnetoresistance.