Understanding Structural Differences Between Bulk Mn2CoFeGe2 Double Half-Heusler Alloy and Deposited Thin Films

Abstract

We report preliminary findings from our study on a new alloy and its thin film form. A double half-Heusler Mn?CoFeGe? alloy was prepared in an arc furnace, and a thin film was deposited on silicon (100) and glass substrates via thermal evaporation. The films were characterized to evaluate their surface morphology and crystal structure using scanning electron microscopy and diffraction analysis. Elemental composition was determined through X-ray spectroscopy. These results highlight the importance of maintaining precise stoichiometry to obtain the intended material properties.

Introduction

Heusler alloys, including Half, Full, Inverse, Binary, and Quaternary types, are increasingly important for technological applications such as sensors, thermoelectric devices, magnetic actuators, and spintronics. Manganese-based (Mn-based) Heusler alloys are particularly notable for their tunable electronic and magnetic properties, strong ferromagnetism, and potential for high-performance magnetic applications.

This study focuses on a newly synthesized Mn?CoFeGe? alloy, a double half-Heusler compound. The material was produced using arc melting, remelting for homogeneity, and annealing at 1000?°C. Thin films were deposited on Si (100) and glass substrates via thermal evaporation and post-annealed for structural uniformity.

X-ray diffraction (XRD) confirmed the crystallinity of the powder sample, while thin films on glass showed limited diffraction due to deposition constraints. Morphological analysis using FESEM revealed that increasing deposition time produced continuous film surfaces from initially granular islands. Energy-dispersive X-ray spectroscopy (EDS) confirmed that both powder and thin-film samples matched the nominal composition of Mn, Co, Fe, and Ge, with homogeneous elemental distribution and no significant inhomogeneities.

Conclusion

In this study, we focused on the Mn?CoFeGe? Heusler alloy and examined it in both bulk and thin-film forms. The bulk sample was prepared by arc melting, with repeated melting steps to ensure proper mixing and uniformity. Thin films of the same material were grown on Si (100) and glass substrates using a thermal evaporation process. To understand the structure and composition of the samples, we used X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS). These techniques helped us confirm the phase formation, crystal structure, and elemental distribution in both the powdered alloy and the thin films. XRD results gave us clear information about the crystalline behavior of Mn?CoFeGe?, while EDS confirmed the stoichiometry and elemental uniformity across the material. Using both techniques together allowed us to gain a better understanding of how the material’s structure relates to its properties. This is particularly important for Heusler alloys, as their tunable magnetic and electronic behavior makes them promising for applications in areas such as spintronics, magnetocaloric devices, and thermoelectric systems.

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Copyright

Copyright © 2025 T. Naaraayanan, M. Saroja, M. Venkatachalam . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.