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.