Magnetic order and noncollinear spin transport of domain walls based on zigzag graphene nanoribbons

Considering exotic spintronic properties, we propose by first-principles calculations that the domain walls (DWs) can form in zigzag graphene nanoribbon (ZGNR). The calculations based on the density functional theory and the non-equilibrium Green's function show that both abrupt and spiral DWs can exist in ZGNR depending on the initial magnetization conditions which can be implemented by the external magnetic field in experiments. Moreover, as the width of DW is small, a spiral DW is preferred. More importantly, the transmission at the Fermi level remains almost unchanged even when the relative angle (θ) between magnetization direction of two leads is up to 135°. Such a characteristic indicates that the slight change in the direction of magnetization of ZGNR-based spintronic devices will not alter the conductance. On the other hand, as the width of DW is large, the magnetization distribution of DW is of spiral nature at small θ, but it will change from the spiral-like to abrupt-like when θ increases.