Z-Site Substitution-Driven Transition From Semiconducting Antiferromagnetism to Half-Metallic Ferromagnetism in FeCrRuSi and FeCrRuP Heusler Alloys

R. Lardjania, b, R. Baghdada, A. Zaouib aPhysics Department, Matter Sciences Faculty, Ibn Khaldoun University of Tiaret, Algeria bComputational Materials Physics Laboratory, Djillali Liabès University of Sidi Bel-Abbès, Sidi

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We report a first-principles density functional theory study employing a modified Becke-Johnson potential of the quaternary Heusler alloys FeCrRuSi and FeCrRuP crystallizing in the Y-type (I) structure. At its equilibrium lattice parameters, FeCrRuSi is predicted to be a semiconducting antiferromagnet, exhibiting an indirect band gap of ~0.69 eV in both spin channels, with the Fermi level located just above the valence-band maximum, indicative of weak n-type character. In sharp contrast, FeCrRuP displays robust half-metallic ferromagnetism, characterized by a metallic majority-spin channel and a minority-spin indirect gap of ~0.72 eV, resulting in 100% spin polarization at the Fermi level. This pronounced change in electronic and magnetic behavior is attributed to a weakening of the d-p hybridization induced by the Z-site substitution. Replacing Si with P leads to a slight lattice expansion, reducing the covalent interactions between the main-group p states and the transition-metal d orbitals. Projected density-of-states analyses reveal that the minority-spin gap in FeCrRuP originates from strong hybridization between P 3p states and transition-metal d states, whereas FeCrRuSi shows a more balanced p-d contribution, consistent with antiferromagnetic order. These results demonstrate that Z-site substitution is an effective route to engineer magnetic order and half-metallicity, identifying FeCrRuP as a promising candidate for spintronic applications.

DOI:10.12693/APhysPolA.149.25 topics: FeCrRuP, quaternary Heusler, electronic structure, half-metallicity