📝 SummarXiv

Abstract

We present a comprehensive investigation of the influence of Ru concentration on the lattice parameters, atomic magnetic moments, electronic structure, and magnetic anisotropy energy of the full Heusler L2$_1$-type Mn$_2$Ru$_{1-x_p}$Ga alloy, where x$_p$ = 0.0834 p with p=0,...,12. This study combines first-principles calculations with data-driven techniques from artificial intelligence, specifically principal component analysis (PCA), to reveal trends and correlations across multiple structural, magnetic, and electronic descriptors. For each composition, a set of inequivalent atomic configurations was fully optimized. Structurally, the relaxed lattices exhibit anisotropic expansion, with a pronounced elongation of the out-of-plane lattice parameter ($c$) relative to the in-plane lattice vectors, which promotes the development of perpendicular magnetic anisotropy. Our results reveal that an out-of-plane easy axis emerges at intermediate Ru concentrations (25-28%), while low and high Ru levels favor an in-plane orientation or even vanishing anisotropy. The half-metallic character is also modulated by Ru content, appearing selectively at both ends of the composition range. Additionally, the ferrimagnetic coupling between Mn(4a) and Mn(4c) sublattices leads to nearly compensated magnetic moments below 50% Ru content, with a net moment close to zero around 30%. These findings open a pathway toward the design of tunable spintronic materials with co-optimized perpendicular magnetic anisotropy and half-metallicity, making Mn$_2$RuGa a promising candidate for magnetic tunnel junctions, magnetoresistive random-access memory (MRAM) devices, and high-density magnetic storage applications.