Cu(1 1 1) supported graphene as a substrate for magnetic dimers with a large magnetic anisotropy: relativistic density-functional calculations.
We report on our relativistic density-functional investigations of the properties of transition-metal dimers adsorbed on a graphene monolayer supported by a Cu(1 1 1) substrate, which extends our studies of dimers in the gas-phase and adsorbed on a freestanding graphene layer (Błoński and Hafner 2014 J. Phys.: Condens. Matter 26 146002). The presence of the Cu(1 1 1) substrate enhances the interaction between the dimer and the support. For homoatomic dimers such as Ir2 and Pt2 a flat adsorption geometry is now preferred over an upright geometry, which is stable on a graphene monolayer. The magnetic moment of the dimer is strongly reduced, the magnetic anisotropy is very low-in contrast to the strong anisotropy of free and graphene-supported Ir2 and Pt2 dimers. For heteroatomic IrCo and PtCo dimers the upright geometry with the Co atom located in a sixfold hollow of the graphene layer is preserved, but the stronger interaction with the support leads to a further enhancement of the large magnetic anisotropy energy of IrCo to 0.2 eV/dimer, while that of PtCo is reduced. The mechanism determining the magnetic anisotropy is discussed in relation to the electronic structure of the dimers.
University of Vienna, Faculty of Physics and Center for Computational Materials Science, Sensengasse 8/12, A-1090 Wien, Austria. Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Kraków, Poland.
P
P
Błoński
J
J
Hafner