Magnetic properties of weak itinerant ferromagnetic ζ-Fe₂N film

We have studied magnetic properties of ζ-Fe2N film deposited onto surface-oxidized Si (100) substrates by reactive dc magnetron sputtering with an argon–nitrogen atmosphere. At the temperature less than 120 K, the magnetic moment of the 120 nm-thick ζ-Fe2N film is hard to be saturated at magnetic fields up to 50 kOe, and the magnetic moment is weak. The inverse susceptibility linearly increases as the temperature increases between 65 and 160 K, and the change of the inverse susceptibility obeys the Curie–Weiss law. From the results of magnetization measurements, the magnetic parameter of the Curie temperature, the spontaneous magnetic moment at 0 K and the effective magnetic moment can be estimated to be 35 ± 2.5 K, 0.028 μB/iron atom and 0.70 μB/iron atom, respectively. These parameters suggest that the ζ-Fe2N film is in the weak itinerant electron ferromagnetic state. These parameters can be also explained by self-consistently renormalization (SCR) theory.