Structural Stability, Mechanical Behavior, Electronic feature, and Half-Metallic Ferromagnetism of Ir₂XGe (X = V, Cr, Mn) Heusler Alloys: Prospective for New Spintronic Devices

Abstract

The present work addresses the limited theoretical understanding of Ir-based full-Heusler alloys Ir₂XGe (X = V, Cr, Mn), whose structural stability and spin-dependent electronic properties remain insufficiently explored. Using the full-potential linearized augmented plane wave plus local orbital (FP-APW + lo) method within density functional theory, structural, mechanical, electronic, optical and magnetic properties were systematically investigated employing both GGA-PBE and the modified Becke–Johnson (mBJ) exchange potential. Total energy calculations confirm that all compounds stabilize in the regular L2₁ structure with a ferromagnetic ground state. The calculated equilibrium lattice parameters are 6.11 Å (Ir₂VGe), 6.07 Å (Ir₂CrGe), and 6.07 Å (Ir₂MnGe). Elastic constants satisfy the mechanical stability criteria for cubic systems, and Pugh’s ratio indicates ductile behavior, particularly for Ir₂MnGe. Ab initio molecular dynamics simulations reveal structural robustness without phase transformation up to 500 K. Electronic structure calculations within mBJ predict half-metallic behavior, characterized by metallic majority-spin states and minority-spin band gaps of 0.47 eV, 0.43 eV, and 0.26 eV for Ir₂VGe, Ir₂CrGe, and Ir₂MnGe, respectively. Integer total magnetic moments of 3, 4, and 5 µB per formula unit follow the Slater–Pauling rule (Mₜ = N_v − 24), leading to a theoretical prediction of 100% spin polarization within the mBJ approximation. These results indicate that Ir₂XGe compounds are promising candidates for spintronic applications.