Growth mode and magnetic behavior of thin Fe films onCu3Au(001) studied by low-energy electron diffraction and spin-resolved electron spectroscopies

The structure and magnetic behavior of ultrathin Fe films on ${\mathrm{Cu}}_3$Au(001) have been examined. By low-energy electron diffraction (LEED) and Auger measurements it is shown that films up to a thickness of 7 monolayers (ML) deposited at room temperature grow pseudomorphically as face-centered-cubic Fe(001) with the ${\mathrm{Cu}}_3$Au lattice parameter of 3.75 Å parallel to the surface. The films grow layer by layer. The magnetism of the fcc Fe films has been investigated by spin-polarized secondary-electron spectroscopy as a function of film thickness. The spin-polarization component parallel to the film plane is zero for films thinner than 3.6 ML. The nonzero spin polarization for films thicker than 3.6 ML indicates the existence of remanent magnetization parallel to the surface at room temperature. Spin-resolved photoelectron spectroscopy with synchrotron radiation has been used to study the electronic and magnetic structure of the films. The high spin polarization P>50% of the photoelectrons clearly demonstrates the ferromagnetism of γ-Fe with a lattice constant of 3.75 Å. The spin-resolved energy distribution curves (SREDC’s) may be understood according to the spin-resolved band-structure calculations of Bagayoko and Callaway [Phys. Rev. B 28, 5419 (1983)]. The results indicate that in contrast to α-Fe, γ-Fe with a lattice parameter of 3.75 Å is a strong ferromagnet.