Ab initio calculation of structural and magnetic properties for Fe mono- and bilayers on Mo(1 1 0)

Abstract

The atomic structures were optimized and magnetic moments calculated for the pseudomorphic Fe overlayers on Mo(1 1 0) substrates employing the all-electron full-potential linearized augmented plane-wave (FP-LAPW) method. Three slabs were considered: (i) 5 monolayer (ML) Mo(1 1 0) substrate, (ii) and (iii) 1 and 2 ML pseudomorphic Fe overlayers on each side of 5 ML Mo(1 1 0) substrate. We found that for the bare Mo substrate, the top Mo–Mo interlayer spacing is contracted by 4.8% with respect to the theoretical bulk Mo(1 1 0) interlayer distance of 2.238 Å. For the 1 ML Fe coverage, the Fe–Mo interlayer spacing has a contraction of 10.3% with respect to the calculated bulk Mo(1 1 0) interlayer spacing, while, for the 2 ML Fe, it is reduced by 9.5%. The Fe–Fe interlayer spacing is also contracted by as much as 11.4% with respect to the theoretical bulk Fe(1 1 0) interlayer distance of 2.004 Å. The inner Mo–Mo interlayer spacings are slightly expanded (<0.5%). The magnetic moment for the 1 ML Fe overlayer on top is enhanced to 2.59 μ B compared to the bulk value of 2.2 μ B. For 2 ML Fe coverage, the magnetic moments are 2.81 μ B and 2.32 μ B for the surface and interface Fe layers, respectively.