The design of bipolar spin filtering junction in zigzag silicene nanoribbons

• The electronic structure of semi- and fully hydrogenated ZSiNRs are investigated.
• The semi-hydrogenation of ZSiNRs can lead to ferromagnetic semiconducting behavior.
• The heterostructure consists of semi-hydrogenation ZSiNRs and ZSiNRs.
• The perfect dual spin filtering effect can be obtained at the parallel and antiparallel spin configuration.

We performed first-principles simulation on the electronic structure of zigzag silicene nanoribbons (ZSiNRs), and found that semi-hydrogenation can break the extended π-bonding network of silicene, leaving the electrons in the unsaturated Si atoms localized and unpaired, and ferromagnetic semiconducting behavior can be obtained. While the fully hydrogenated ZSiNRs are found to be energetically degenerate and show wide band-gap semiconductor feature. Then, we designed and investigated the spin-dependent electron transport of a heterostructure, consisting of semi-hydrogenation ZSiNRs and ZSiNRs. The results show a perfect dual spin filtering effect at the parallel and antiparallel spin configuration with large bias range. The spin dependent electron transmission spectrum, band structure, transmission pathway, and the molecularly projected self-consistent Hamiltonian state are employed to investigate the physical origin of the spin-polarized effect.

It is notable that the current of α-spin electron through the system increases rapidly at the negative bias, while it is almost forbidden within the positive bias range. More interestingly, the β-spin electron can easily pass through the system at the positive bias, while it is almost forbidden within the negative bias range. The spin filtering efficiency (SFE) is higher than 95% at high biases. On the other hand, the maximum rectification ratio (RR) of spin current reaches 105, which is quite comparable to that of the typical solid-state rectifier.Figure optionsDownload as PowerPoint slide