Even-odd chain dependent spin valve effect on a zigzag biphenylene nanoribbon junction

The even-odd chain dependent spin valve effect was forecasted in some honeycomb graphene-like materials with zigzag edges. In this study, we confirm that the even-odd chain related spin valve phenomenon also exists in a zigzag biphenylene nanoribbon (ZBN) junction. By modeling the ZBN junction with different even and odd chains subjected to a local Rashba spin-orbit coupling (SOC) and a homogeneous magnetic field, we calculate the spin dependent conductance spectra between the source and the drain electrodes and find that the spin up (down) electron can be inhibited (allowed) to flow through the even (odd)-chain ZBN junction, which can be explained by the combined effect between the pseudo-parity conservation and magnetic field-tunable energy gap in the energy band theory. The switch on and off states of spin valve can be modulated by the most system parameters such as the Fermi energy, magnetic flux, and Rashba SOC. Furthermore, the ZBN can act as a gate-tunable spin generator and spin filter, in which we can get 100% polarized spin up (down) electrons with (no) spin-flipping from the even-chain ZBN junction, and only produce 27% polarized spin-converting electrons from the odd-chain ZBN junction. Our findings might be useful in designing future multi-parameter controllable spin valves by using the new carbon allotropes.