  We have investigated different geometries of two dimensional (2D) infinite
length Ni nanowires of increasing width using spin density functional theory
calculations. Our simulations demonstrate that the parallelogram motif is the
most stable and structures that incorporate the parallelogram motif are more
stable as compared to rectangular structures. The wires are conducting and the
conductance channels increase with increasing width. The wires have a
non-linear behavior in the ballistic anistropic magnetoresistance ratios with
respect to the magnetization directions. All 2D nanowires as well as Ni (111)
and Ni (100) monolayer investigated are ferromagnetic under the Stoner
criterion and exhibit enhanced magnetic moments as compared to bulk Ni and the
respective Ni monolayers. The Stoner parameter is seen to depend on the
structure and the dimension of the Nws. The easy axis for all nickel nanowires
under investigation is observed to be along the wire axis. The double
rectangular nanowire exhibits a magnetic anomaly with a smaller magnetic moment
when compared to Ni (100) monolayer and is the only structure with an easy axis
perpendicular to the wire axis.
