Electronic and magnetic properties of the fcc Fe(001) thin films: Fe/Cu(001) and Cu/Fe/Cu(001)

Abstract

All-electron total-energy local-spin-density studies of the electronic and magnetic properties of fcc Fe(001) as overlayers or sandwiches with Cu(001) were undertaken in order to understand the following: (1) the surface (interface) magnetism of fcc Fe(001), (2) the effect of nonmagnetic Cu on the magnetization of Fe and (3) the effect of the reduced coordination number on the magnetic coupling of Fe layers near the surface and interface. From our systematic studies of (i) one and two layers of Fe on Cu(001) and (ii) one and five layers of Fe sandwiched by Cu, it is concluded that the Fe magnetic moment is enhanced on the surface (to 2.85${\mathrm{mu}}_B$) and the surface (interface) Fe layer is predicted to couple ferromagnetically to the subsurface (subinterface) Fe layer (in contrast to the antiferromagnetic behavior in the bulk fcc Fe). The effect of the nonmagnetic Cu overlayers decreases slightly (by 0.25${\mu }_B$) the magnetic moments of Fe at the Fe/Cu interface from those of the free-standing surfaces, indicating the persistence of the two-dimensional magnetization at the interface. Magnetic hyperfine fields are compared among various magnetic states; the interface Fe atoms are found to experience a larger hyperfine field than the inner layers for the magnetic ground state due to the retention of antiferromagnetic coupling between Fe layers away from the interface. Electronic charge-density, work-function, and single-particle spectra are presented and discussed. The calculated energy dispersions agree well with a recent photoemission measurement by Onellian et al.