h-BN as a perfect spin splitter in ferromagnetic zigzag graphene nanoribbons

The manipulation of spin transport is always a central task in spintronics and two very well-known findings along this line thus far are the observations of half-metallicity and pure spin current, both very important in practical applications. In this paper, we propose another control over spin, termed as a spin splitter, with an aim to split the two spin channels from the spatially overlapped paths into two isolated branches. Based on a density functional study, we implement this idea in ferromagnetic zigzag graphene nanoribbons (ZGNRs) and find that h-BN nanoribbon embedded in the ZGNR acts as a perfect spin splitter. It originates from the different interfacial dipoles developed at the N-C and B-C interfaces and the subsequent different built-in transverse electric fields, which drives the two narrow side ZGNRs into half-metallicity with different spin polarity. The findings will be of great significance in spintronics.