Spin filtering controller induced by phase transitions in fluorographane.

The electronic and transport properties of fluorographane (CHF) nanoribbons, , bare (B-CHF) and hydrogen-passivated (H-CHF) CHF nanoribbons, are extensively investigated using first-principles calculations. The results indicate that edge states are present in all the B-CHF nanoribbons, which are not allowed in the H-CHF 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 sp hybridization at the edge. The H-CHF nanoribbons are semiconductors with wide band gaps. However, the band gap of B-CHF 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-CHF 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 CHF nanoribbons in spintronic devices.