Even-odd chain dependent spin-switching phenomena in zigzag and armchair <i>β</i> -graphyne nanoribbon ferromagnetic junctions

We theoretically study spin-switching devices based on ultra-thin<i>β</i>-graphyne nanoribbon(GYNR) ferromagnetic junctions with zigzag and armchair edges. Using the tight-binding approximation and Keldysh Green's function method, we find that the spin switching phenomenon not only appears in an even-chain zigzag-edged<i>β</i>-GYNR junction ruled by so-called valley-valve effect, but also exists in an armchair-shaped one due to its band gap, which is quite different from the case of graphene due to the Klein tunneling effect. The switching state of spin transport induced by the gate-switching transition from conductor to insulator can be influenced by the device's edges, chain numbers, Fermi energy and magnetization configuration, which can be explained by energy band theory for zigzag and armchair<i>β</i>-GYNR junctions respectively. This model may have potential research significance for overcoming the Klein tunneling effect in graphene structures and manufacturing spin switches by using this new<i>β</i>-GYNR junction.