Investigating the Phonon Spectral Properties of Nickel and Palladium-based Heusler Alloys

This study delves into the phonon spectra, martensitic transformations, and magnetic properties of NiMnGa, NiMnAl, and PdMnZ (Z = Ga, Ge, As) alloys.Focusing on NiMnGa, we observe a martensitic transformation at 202 K, closely related to a pre-transformation phase at 260 K, reflecting the compound's sensitivity to temperature and external influences.Investigations into supercell size and geometry reveal a significant impact on the martensitic elasticity and stability of the TA phonon mode in NiMnGa and NiMnAl.Chemical and structural disorders, especially in NiMnGa, show pronounced effects on crystallographic structures and superelastic properties.Computational analysis using VASP software with PBE and SCAN methodologies highlights differences in the TA phonon mode, indicating the complexities in metallic properties and structural instabilities.The PdMnZ series exhibits diverse magnetic and martensitic behaviours, with the theoretical study underscoring the influence of valence electrons on compound stability.These provide a deeper understanding of the relationship between atomic-level phenomena and macroscopic properties in these complex alloys, paving the way for future research and applications in advanced material science.