Single Magnetic Atom on a Surface: Anisotropy Energy and Spin Density

Studying single-atom magnetic anisotropy on surfaces enables the exploration of the smallest magnetic storage bit that can be built. In this work, magnetic anisotropy of a single rare-earth atom on a surface is studied computationally for the first time. The single adatom and its substrate surface are chosen to be a Dysprosium (Dy) atom and a copper-nitrite surface, respectively, where single transition-metal magnetic atoms on the same surface were previously studied one atom at a time by scanning tunneling microscopes. We propose unconventional f and d subshell symmetries so that following the first-principles calculations, simple pictorial analyses of the spin-density distribution can be performed for the first time, independently for both a rare-earth atom Dy and a transition-metal Fe. The magnetic anisotropy energy of Dy on the surface is calculated to be a factor of five larger than the previous highest one, reaching a record-high value of 31 meV.