Strain induced giant magnetism in epitaxial Fe16N2 thin film

We report a direct observation of giant saturation magnetization in Fe16N2. By exploiting thin film epitaxy, which provides controlled biaxial stress to create lattice distortion, we demonstrate that giant magnetism can be established in Fe16N2 thin film coherently grown on MgO (001) substrate. Explored by polarized neutron reflectometry, the depth-dependent saturation magnetic induction (Bs) of epitaxial Fe16N2 thin films is visualized, which reveals a strong correlation with the in-plane lattice parameter and tensile strain developed at near substrate interface. With controlled growth process and dimension adjustment, the Bs of these films can be modulated over a broad range, from similar to 2.1 Tesla (T) (normal Bs) up to similar to 3.1 T (giant Bs). (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4792706]