First-principles Simulations of Atomic Structure and Magnetism in Fe nanoparticles

摘要

The properties of small clusters Fe_3 and Fe_5, in which the non-collinearity of magnetic density is expected to be important, and of larger nanoparticles (consisting of up to 62 atoms) are studied from first principles making use of density functional theory, norm-conserving pseudopotential and numerical local orbitals method, as implemented in the Siesta code. We concentrate on the interplay of lattice relaxation, mostly pronounced near the surface of particles, and the particles' magnetic characteristics. Previously obtained theoretical findings of enhanced magnetic moments in outer shells of nanoparticles are confirmed. These results are refined by taking structure relaxation into account and by considering more representative bcc- and fee-related particles; moreover, we allowed antiferromagnetic ordering along with ferromagnetic one.