Magnetic properties of Co nanowires on Cu(001) surfaces

Abstract

We present ab initio calculations for spin and orbital moments of finite ${\mathrm{Co}}_{n}$ $(n=1,3,5,7,9)$ nanowires on Cu(001) surfaces, performed using the linear muffin tin orbital atomic sphere approximation method implemented directly in real space (RS-LMTO-ASA), in which the spin-orbit coupling and the orbital-polarization term have been included. For Co as an adatom on Cu(001) we predict an extremely large orbital moment, which is comparable to the spin moment. Our investigations for Co nanowires on Cu(001) address the persistence and extent of this large orbital moment in the wires as a function of their size. We find that the average orbital moment $({M}_{\mathrm{orb}})$ per Co atom decreases as the size of the wire is increased, and this behavior is strongly correlated with the coordination number of the Co atoms. The magnetic moments per atom of very long nanowires inferred from the present finite nanowire calculations are in good agreement with those given in the literature for ideal infinite wires on Cu(001).