Magnetic anisotropy of vicinal (001) fcc Co films: Role of crystal splitting and structure relaxation in the step-decoration effect

Abstract

The uniaxial in-plane magnetic anisotropy (UIP-MA) constant is calculated for a single step on the (001) surface of fcc Co(N ) films. The calculations are done for both an undecorated step and the step decorated with one or more, up to 7, Cu wires. Our objective is to explain the mechanisms by which the decoration decreases the UIP-MA constant, which is the effect observed experimentally for ultrathin Co films deposited on vicinal (001) Cu surfaces and can lead to reorientation of magnetization within the film plane. Theoretical calculations performed with a realistic tight-binding model show that the step decoration changes the UIP-MA constant significantly only if the splitting between the on-site energies of various d-orbitals is included for atoms located near the step edge. The local relaxation of atomic structure around the step is also shown to have a significant effect on the shift of the UIP-MA constant. The influence of these two relevant factors is analyzed further by examining individual contributions to the UIP-MA constant from atoms around the step. The magnitude of the obtained UIP-MA shift agrees well with experimental data. It is also found that an additional shift due to possible charge transfer between Cu and Co atoms is very small.

Electric field control and effect of Pd capping on magnetocrystalline anisotropy in FePd thin films: A first-principles study

“…It is worth mentioning that our calculations for the 9-ML-thick FePd film exhibit a similar oscillatory behavior as a function of Pd thickness, indicating that the capping effect is robust and its origin lies on the change of the electronic structure of the Pd cap upon varying its thickness, which is discussed below. The oscillation of the MCA versus Pd cap thickness is consistent with that found in thin Co films, where the uniaxial magnetic anisotropy oscillates as a function of film thickness with a period of about 2.3 atomic layers [31][32][33][34]. Figure 10 shows the total Pd d-derived DOS projected on and averaged over all MLs in the Pd cap.…”

Experimental confirmation of quantum oscillations of magnetic anisotropy in Co/Cu(001)

“…Since covering with Au does not change the volume contribution to the uniaxial anisotropy, it does not meaningfully impact the oscillation amplitude. 3,10 In Fig. 3, the experimental data are compared to the band energy contribution to the MAE calculated per surface atom by Szunyogh et al 1 In the case in which the Co film is covered by 1 ML of Au, the magnitude of H s is reduced even further and stays close to H s = 0 between 8 and 14 ML of Co (compare Fig.…”

“…Later, the calculations were extended to Co films on vicinal Cu(001), where the uniaxial magnetic anisotropy was found to oscillate with a period close to 2 ML, as well. 3 These predictions, made nearly 15 years ago, have so far not been confirmed experimentally. This is not surprising since oscillations with a period of 2 ML can be easily diminished if the vertical amplitude of surface roughness is large.…”

“…[4][5][6] The formation of QWSs can directly alternate the electronic structure at the Fermi level and therefore result in oscillatory physical properties such as magnetic anisotropy. 2,3,[7][8][9][10][11] For (001) face-centered-cubic (fcc) Co films, theory predicts oscillations of the magnetocrystalline anisotropy energy (MAE) as a function of film thickness. 1,2 Szunyogh et al 1 performed layer-resolved ab initio-like calculations for Co slabs consisting of N atomic layers (monolayers, ML).…”

Noble metal capping effects on the spin-reorientation transitions of Co/Ru(0001)

“…In addition, hybridization at the interface alters the distribution of electronic levels and subsequently the magnetic properties of both the magnetic film and the polarized cap material, with a direct impact on the MAE. Some Co-based thin film systems, such as those including Cu, Au and Pt [22,23,24,20,25], have received more attention in the literature than Co/Ru [26,27,28,29,26,30]. Nonetheless, Co/Ru is a particularly interesting prototypical system.…”