Structure and magnetic properties of sputtered Co-Si alloy films

An interesting behavior of Si as an additive to Co alloys is expected, since Si is supposed to change the structure and the magnetic properties of Co alloys as a metalloid element. From the above reason, the relationship between the microstructures and the magnetic properties of the sputtered Co-Si alloy films was investigated in detail. As the Si content was increased to 35 at. % Si, such changes of magnetic properties were found that the coercive force of the sputtered Co-Si alloy films reached the peak of about 550 Oe at 6-10 at. % Si, below or above which the coercive force is relatively small. On the other hand, according to the transmission electron microscopic observation at relatively low magnification, the grain size of α-Co crystallites forming the films was found to decrease as the Si content increases. The results of Lorentz electron microscopy showed large magnetic domains in the films with a Si content below 6 at. %, very fine magnetic domains in the films with 6-10 at. % Si content, and the disappearance of magnetic domains in the films with greater than 25 at. % Si. From the above, it can be mentioned that the magnetic properties of the sputtered Co-Si alloy films are very closely related to the microstructures and/or the magnetic domain structures.