Growth of Fe silicides on Si(111) surfaces from bcc-Fe to fine-polycrystal and β-FeSi2 phases: Structure and magnetism

We studied the structure and magnetism of the bcc-Fe(111) phase to the fine-polycrystal and β-FeSi2 phases in solid phase epitaxial growth of iron silicides on Si(111) surfaces. In the polycrystal phase displaying Debye rings in reflection high-energy electron diffraction, we found randomly-oriented bcc-Fe fine-crystals to be responsible for the phase, and obtained ferromagnetic hysteresis but the magnetization was small. In the polycrystal phase, other irons and silicides were sometimes included: epitaxially-grown bcc-Fe crystals with preferential orientation in different directions, and β-FeSi2(101) or (110) layers. We show a growth scheme with annealing for structure and magnetism of these phases.