Absolute magnetometry on ultrathin 3d-metal films by UHV-SQUID

Recently a combination of SQUID magnetometry with an UHV chamber and cooling capabilities was developed. This allows us to measure the remanent magnetization in statu nascendi with submonolayer sensitivity. Co and Ni films 2–20 monolayers (ML) thick were grown on Cu(0 0 1) and measured at temperatures between 40 and 300 K. We deduced separately surface and interface magnetic moment contributions by analyzing thickness-dependent moments of Co/Cu(0 0 1) and Cu/Co/Cu(0 0 1). The surface atoms are shown to carry a 32(5)% enhanced moment, while the interface moment is reduced by 17%. For the case of Ni thin films, the magnetization is almost bulk-like. Cu capping reduces the magnetization by 22% at 4 ML film thickness.