Unconventional ferromagnetic transition in the disordered NiCoFeCr high entropy alloy

We present a structural, magnetic, and transport study of equiatomic NiCoFeCr, a high-entropy alloy (HEA) forming a chemically disordered face-centered cubic (fcc) solid solution. Atomic-scale characterization confirms a homogeneous elemental distribution without detectable segregation. The dc magnetization deviates from mean-field predictions, exhibiting critical behavior consistent with short-range Heisenberg-type magnetic interactions. Scaling analysis yields critical exponents (β = 0.348, γ = 1.347, δ = 4.871) in line with the three-dimensional Heisenberg universality class. The magnetic exchange interaction decays as J(r) ∼ r^−4.9, confirming short-range coupling. Spin correlations emerge in the paramagnetic (PM) regime and intensify near 125 K, evidenced by a peak in magnetic entropy, preceding the ferromagnetic (FM) Curie transition at 92 K. The 125 K magnetic anomaly is also manifested in transport properties via a resistivity crossover and strong suppression of the anomalous Hall effect, suggesting an intrinsic spin-dependent scattering origin. The observed high carrier concentration coupled with low mobility underscores the critical role of disorder-induced scattering, inherently associated with the chemically disordered fcc lattice.