Almost "magnetic dead" of the Co layer in Co/Zr-3 superlattice

The magnetic and electronic properties of Co/Zr-3(0001) superlattice and un supported Co and Zr monolayers (ML) with the hcp bulk Zr two dimensional la ttice parameters have been calculated by employing the full potential linea rized augmented plane wave (FLAPW) method with general gradient approximati on (GGA) for exchange-correlation potential. The unsupported Zr and Co ME w ere calculated to be stable in paramagnetic and ferromagnetic states, respe ctively. The magnetic moment of the unsupported Co ML was 2.08 mu(B). The C o-Zr interlayer spacing of the Co/Zr-3 superlattice was calculated to be re duced significantly by 9.80 % compared to that expected from Co and Zr bulk assuming preservation of the atomic volumes. On the other hand, the Zr-Zr interlayer spacing was calculated to be enhanced by 3.35 % compared to that of bulk Zr. Both of the reduced Zr-Co and the enhanced Zr-Zr interalyer sp acings decreased the magnetic moment of Co and eventually led to almost "ma gnetic dead" (0.33 mu(B)). Suprisingly, the Zr-Zr bond was weakened faster than the Zr-Co bond as the Zr-Zr spacing increased. This may explain the re ason why Co atoms diffuse into a Zr surface and amorphization takes place a t the interface when Co atoms adsorb on a Zr surface. We will discuss the p hysical origin of the relation between magnetism and interlayer interaction .