Structural, magneto-static and magneto-dynamic properties of Fe substituted Ni-Mn-In films

Off-stoichiometric Ni-Mn-In films of 500 nm thickness were deposited on Si (100) substrate by dc magnetron sputtering at ambient temperature. As-deposited films were annealed ex situ at 550 °C and 700 °C for 1 h under high vacuum. As-deposited Ni-Mn-In films which were amorphous, exhibited orthorhombic martensite structure upon annealing. The amorphous film was found to be paramagnetic whereas the annealed (martensite) film exhibited weak ferromagnetic behavior. Fe substituted Ni-Mn-In films of the same thickness annealed at 550 °C exhibited orthorhombic martensite structure, whereas films annealed at 700 °C exhibited dual phase (cubic L21 austenite and orthorhombic martensite) structure. Martensite Ni-Mn-Fe-In films showed large magnetic moment as compared to the ternary alloy film. Interestingly, films with dual phase structure yielded much higher magnetic moment. Ni-Mn-Fe-In films with higher thicknesses annealed at 700 °C showed enhanced magnetic moment due to higher L21 phase content in them. Analysis of polar angle variation of resonance field and linewidth of the dual phase Ni-Mn-Fe-In films revealed very low effective perpendicular magnetic anisotropy (3.0 × 103 J/m3) and low Gilbert damping constant (0.009 ± 0.001) for the first time. The new results obtained are interpreted in terms of the crystalline nature of the films.