Abstract: Ultrathin Fe films were epitaxially grown on Si(111) by using an ultrathin iron silicide film with $p(2\times2$) surface reconstruction as a template. The surface structure and magnetic properties were investigated in situ by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM), and surface magneto-optical effect (SMOKE). Polar SMOKE hysteresis loops demonstrate that the Fe ultrathin films with thickness $t<6$ ML (monolayers) exhibit perpendicular magnetic anisotropy. The characters of $M$--$H$ loops with the external magnetic field at difference angles and the angular dependence of coercivity suggest that the domain-wall pinning plays a dominant role in the magnetization reversal process.   

Key words: molecular beam epitaxy, surface magnetism, magnetization reversal, Kerr effect