Structural, microstructural and magnetic investigations on the epitaxially grown Ni2MnGa(010) films on MgO(100) substrate

• Ni2MnGa film with room temperature martensitic phase has been epitaxially grown on MgO (100) substrate.
• Film exhibits 45° in-plane rotated growth with an orientation relationship of Ni2MnGa (010) {101} || MgO (001) {110}.
• The film exhibit an excellent crystal quality with dislocation density as low as 6 × 109 cm−2.
• TEM investigations shows hierarchical microstructure and presence of secondary nano-twins.
• A clear indication of magnetic field induced reorientation of martensitic variants is observed as a change in slope of M-H curve.

We report the epitaxial growth of Ni2MnGa thin films on MgO(100) substrate deposited at elevated temperature using direct current magnetron sputtering. The structural and texture analysis of as-deposited film reveal the (010) crystallographic orientation with seven modulated martensite phase and an epitaxial relationship of Ni2MnGa(010){101} || MgO(001){110} between the film and the substrate. The crystal quality of the films was analysed by performing symmetric and asymmetric rocking curve measurements and dislocation density for screw and edge dislocations is determined to be 6 × 109 cm−2 and 3.45 × 1010 cm−2, respectively. The presence of micro-twins at an angle of 45° with respect to growth direction and seven modulated nano-twins formed by adaptive modulation has been observed with transmission electron microscopy investigations. The magnetic measurements indicates magnetic field induced reorientation of martensitic variants, strong magneto-crystalline anisotropy and a very high saturation magnetization (IS) of 61 emu g−1 in the film.

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