Structural and magnetic properties of epitaxially grown Fe endash Sm and Fe endash Sm endash N films

Thin Fe endash Sm endash N films with thickness ≥50 nm and coercivities ≥4 kOe were grown on an α-Ta (110) substrate by dc magnetron sputtering. Transmission electron microscopy diffraction data clearly showed that the films were polycrystalline with the ThMn12 tetragonal structure and with a preferential orientation of (011) Fe endash Sm//(110) Ta. This resulted in a uniform distribution of the easy axis on a cone of 29 degree to the film normal. The structural data were also supported by the hysteresis loops measured as a function of angle in plane and out of plane. The high coercivity phase was obtained from targets with 15 endash 20 at.% Sm. For the 10 at.% Sm target, only a soft α-Fe phase was formed. For films of <50 nm sputtered from 15 to 20 at.% Sm, a soft phase was clearly observed in the vibrating sample magnetometer and was the only soft phase formed in 10 nm thick films. However, films of >50 nm thickness showed high coercivities without a kink in the demagnetization loops and seemed to be composed only of magnetically hard phase, which was probably due to strong magnetic interactions between magnetically soft and hard phases at the Fe endash Sm/Ta interface. copyright 1997 American Institute of Physics