An experimental and theoretical investigation on structure-property correlation of Cu₂Mn₁Al_1−xGa_x full-Heusler alloy

The present study reports the evolution of microstructure and magnetic properties of Cu₂MnAl_1−xGa_x Heusler alloys. The L2₁ phase, which remained stable up to a Ga substitution of x = 0.3, transformed into mixed phases, i.e., hexagonal close packed (HCP) and complex cubic structure (CCS) on further addition of Ga. The non-monotonic increase in the lattice constant indicates that some amount of Ga retains its monovalent state. The magnetic phase showed a transition from ferromagnetic to paramagnetic state with increasing Ga concentration. The re-entrant temperature (T_R) decreased from 8.2 K to 5.2 K as Ga content increased from 5 at% to 10 at%. The strength of magnetic exchange-coupling also reduced with an increase in Ga content. Gaussian process regression (GPR) was used to estimate the lattice parameter using the ionic radii and Pauling electronegativity of the constituents. The modeling approach showed high accuracy and stability, providing new insights into future alloy development.