Understanding Magnetic Exchange Interactions by the Pressure Dependent Curie Temperature in FeCoNiCuMn High Entropy Alloys

We report the pressure (P) dependent Curie temperature, T c (P) in a FeCoNiCuMn high entropy alloy (HEA). We analyze T c (P) in terms of d-orbital contraction to explain changes in magnetic exchange interactions (J ex ). Considerations of the d-radius contraction inferred from the composition dependence of T c in γ-Fe-Ni are combined with experimental data for P-dependent lattice constants and magnetic measurements of T c (P), to calculate contributions of atomic spacing and d-orbital radii to J ex . We show the d-orbital contraction with P captures most of the T c variation in this alloy.