Spin-valley filter and tunnel magnetoresistance in asymmetrical silicene magnetic tunnel junctions

The spin and valley transports and tunnel magnetoresistance are studied in a silicene-based asymmetrical magnetic tunnel junction consisting of a ferromagnetic tunnel barrier, sandwiched between a ferromagnetic electrode and a normal electrode. For such an asymmetrical silicene junction, a general formulism is established. The numerical results show that the spin-valley resolved conductances strongly depend on the magnetization orientation of the ferromagnetic tunnel barrier, and the fully spin-valley polarized current can be realized by tuning a perpendicularly applied electric field. We also find that the tunnel magnetoresistance in this case can be effectively modified by the external electric field when the conductance is fully spin-valley polarized. In particular, the exchange field in the ferromagnetic electrode can further substantially enhance the tunnel magnetoresistance of the system. Our work provides a practical method for electric and magnetic manipulation of valley/spin polarization and tunnel magnetoresistance.