Stress-induced Martensitic transformation in epitaxial Ni-Mn-Ga thin films and its correlation to optical and magneto-optical properties
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866908437715091456 |
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| author | Makeš, M. Zázvorka, J. Hubert, M. Veřtát, P. Rameš, M. Zemen, J. Heczko, O. Veis, M. |
| author_facet | Makeš, M. Zázvorka, J. Hubert, M. Veřtát, P. Rameš, M. Zemen, J. Heczko, O. Veis, M. |
| contents | The optical and magneto-optical properties of thin epitaxial Ni-Mn-Ga films, with thicknesses ranging from 8 to 160 nm, were investigated across the spectral range of 0.7-6.4 eV. The films were deposited by DC magnetron sputtering on MgO substrate with stress-mediating Cr buffer layer. Structural and magnetic characterization revealed an stress-induced martensitic transformation for the films thicker than 80 nm, while thinner films remained in austenite structure deformed by substrate constraint. Both X-type and Y-type twin domains were observed in martensitic samples. Magneto-optical polar Kerr effect spectra showed notable evolution with film thicknesses, demonstrating changes in electronic structure of Ni-Mn-Ga. A combination of spectroscopic ellipsometry and magneto-optical Kerr spectroscopy allowed for the deduction of the spectral dependence of full permittivity tensor of investigated samples. Three magneto-optical transitions were fitted to the spectra of non-diagonal permittivity using semiclassical theory, showing strong correlations with in-plane coercivity. Observed correlations highlight the impact of substrate-induced strain on Ni-Mn-Ga films and provide insights into the electronic structure changes associated with the martensitic transformation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_04907 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Stress-induced Martensitic transformation in epitaxial Ni-Mn-Ga thin films and its correlation to optical and magneto-optical properties Makeš, M. Zázvorka, J. Hubert, M. Veřtát, P. Rameš, M. Zemen, J. Heczko, O. Veis, M. Materials Science The optical and magneto-optical properties of thin epitaxial Ni-Mn-Ga films, with thicknesses ranging from 8 to 160 nm, were investigated across the spectral range of 0.7-6.4 eV. The films were deposited by DC magnetron sputtering on MgO substrate with stress-mediating Cr buffer layer. Structural and magnetic characterization revealed an stress-induced martensitic transformation for the films thicker than 80 nm, while thinner films remained in austenite structure deformed by substrate constraint. Both X-type and Y-type twin domains were observed in martensitic samples. Magneto-optical polar Kerr effect spectra showed notable evolution with film thicknesses, demonstrating changes in electronic structure of Ni-Mn-Ga. A combination of spectroscopic ellipsometry and magneto-optical Kerr spectroscopy allowed for the deduction of the spectral dependence of full permittivity tensor of investigated samples. Three magneto-optical transitions were fitted to the spectra of non-diagonal permittivity using semiclassical theory, showing strong correlations with in-plane coercivity. Observed correlations highlight the impact of substrate-induced strain on Ni-Mn-Ga films and provide insights into the electronic structure changes associated with the martensitic transformation. |
| title | Stress-induced Martensitic transformation in epitaxial Ni-Mn-Ga thin films and its correlation to optical and magneto-optical properties |
| topic | Materials Science |
| url | https://arxiv.org/abs/2507.04907 |