STM and SQUID studies of quantum engineered Co magnetic nanoplateles on Si.

Self-organized Co platelets with uniform size and shape were grown on a template of ordered Al cluster arrays on Si(111)-7$\times $7 surfaces. The Al nanocluster array not only suppresses reaction between Si and Co, but also enables formation of well-defined Co nanoplatelets. These platelets are equilateral triangles with fixed orientation and two-monolayer thickness, and the area of individual platelets is half of N$^{2}$ of the 7$\times $7 unit cells. Despite their small volume (a few nm$^{3})$, these magnetic nanoplatelets exhibit unusually high blocking temperature ($>$100 K). The hysterisis curves obtained for these platelets suggest that easy axis of magnetization is perpendicular to the substrate plane. The perpendicular magnetization, high blocking temperature and growth on a silicon surface may make these platelets appealing for technological applications.