Half-metallicity in zigzag phosphorene nanoribbons with magnetic edges

Phosphorene nanoribbons with magnetic edges are potentially attractive for nanoelectronic and spintronic applications. Here, the attention is focused on electronic and magnetic properties of these materials. Using a self-consistent computational method it is shown that, in general, two types of configuration with spontaneous edge magnetization can be responsible for lifting the spin degeneracy, and consequently for the appearance of the half-metallic behavior. Namely, in addition to the well-known configuration with edge states ferromagnetically coupled along each edge and aligned in parallel between the two edges, there is another one (much less explored) with edge states ferromagnetically aligned on only one edge. The ground state magnetic configurations strongly depend on the chemical potential position (electron filling factor), and can be controlled by means of the external perpendicular gate voltage, and by changing the nanoribbon width. It is also shown that the magnetic edge configurations responsible for the half-metallicity can be stabilized with ferromagnetic substrates, due to the proximity effect.