Spin Filtering Controller Induced by Phase Transitions in Fluorographane

The electronic and transport properties of fluorographane (C2HF) nanoribbons, i.e., bare (B-C2HF) and hydrogen-passivated (H-C2HF) C2HF nanoribbons, are extensively investigated using first-principles calculations. The results indicate that edge states are present in all the B-C2HF nanoribbons, which are not allowed in the H-C2HF nanoribbons regardless of the directions. The spin splitting phenomenon of band structure only appears in the zigzag direction. This behavior mainly originates from the dehydrogenation operation, which leads to sp2 hybridization at the edge. The H-C2HF nanoribbons are semiconductors with wide band gaps. However, the band gap of B-C2HF nanoribbons is significantly reduced. Remarkably, the phase transition can be induced by the changes in the magnetic coupling at the nanoribbon edges. In addition, the B-C2HF nanoribbons along the zigzag direction show optimal conductivity, which is consistent with the band structures. Furthermore, a perfect spin filtering controller can be achieved by changing the magnetization direction of the edge C atoms. These results may serve as a useful reference for the application of C2HF nanoribbons in spintronic devices.