Ballistic conductance and magnetism in short tip suspended Ni nanowires

Electronic and transport properties of a short Ni nanowire suspended between two semi-infinite ferromagnetic Ni leads are explored in the framework of density-functional theory. The spin-dependent ballistic conductance of the nanowire is calculated using a scattering-based approach and the Landauer-Buttiker formula. The total calculated conductance in units of G(0)=2e(2)/h is around 1.6, in fairly good agreement with the broad peak observed around similar to 1.5 for the last conductance step in the break junctions. Separating contributions from different spins, we find nearly 0.5G(0) from the majority spin s-like channel, whereas the remaining minority spin conductance of 1.1G(0) contains significant contributions from several d states, but much less than 0.5G(0) from s states. The influence of the structural relaxation on the magnetic properties and the ballistic conductance of the nanowire is also studied.