RESUMO
The electronic properties of Tm and Lu atoms adsorbed on nanoscale Cu2N insulating islands and on a clean Cu(100) surface have been investigated by scanning tunnelling microscopy and spectroscopy, and density functional calculations modelling the electronic structure of the rare earth atoms were performed. While Lu adatoms display the same spectra on both surfaces, tunnelling spectra of Tm on Cu2N indicate a state at ≃0.8 V or ≃1.9 V bias, depending on the 4f population of the adatom, 4f12 or 4f13, which is not present on Tm atoms adsorbed on Cu(100). Although inelastic 4f-spin-flip excitations were not detected, variation of tunnelling through the strongly correlated d-electrons indicates that the insulating layer opens a pathway to access the electronic state of those 4f electrons in the single adatom.
RESUMO
High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.
