Effect of oxygen on the Mn–Co ferromagnetic coupling

Density-functional study of oxidation at the Mn–Co interface

“…The energy ordering is even quantitatively the same when the local or other non-local-density functionals are applied in the non-self-consistent way as mentioned above. The only exception is the MnCo alloy overlayer where the local functional reverses the stability of F and AF coupling similarly as in previous models [7,8]. The energy difference is surprisingly small but the result is stable with respect to some model modifications ( Table 1).…”

“…0039 A number of experimental studies has been devoted [3][4][5][6] to Mn deposition upon ultrathin fcc Co(0 0 1) films grown on Cu(0 0 1). The recent tight-binding linear-muffin-tin-orbital (TB-LMTO) calculations [7,8] performed in the atomic-sphere-approximation [11] arrive at the accord with experiment (a (2 · 2) superstructure with ferromagnetic coupling of Mn to the Co film) by finding the ordered surface Mn-Co alloy as the stable structure. It appeared important, however, to use density functional in a generalized-gradient approximation form to get the correct answer.…”

“…Refs. [7,8]): (1-2) Mn(1 · 1) overlayer that couples ferromagnetically or antiferromagnetically to Co, (3) Mn(2 · 2) overlayer with surface antiferromagnetic arrangement of spins, (4-5) ordered MnCo alloy overlayer ( Fig. 1) with magnetic moments of Mn oriented parallel or antiparallel to cobalt moments.…”

“…Recently the present authors have discussed the effect of oxygen on the MnCo coupling at the surface of Co(0 0 1) within a TB-LMTO code [8]. However, it is well-known that such code is unable to compute the forces acting on each atom so that geometrical optimization was not performed.…”

“…It is now well-documented that the magnetic configurations as well as the values of the magnetic moments depend strongly on the distances between atoms. In order to improve the previous results we adopt a density-functional pseudopotential code which allows us to perform geometry optimization for several structures which makes conclusions much more reliable than in the previous theoretical study [8].…”