Valley And Spin Polarization Transport In Ferromagnetic Silicene/Graphene Superlattice

Two-dimensional material has been a topic of intense research in condensed matter physics since the successfully synthesized of a mono-layered graphene by the Geim team in the Manchester University,which promotes the development of spintronics and valleytronics at the same time.In recent years,besides graphene,a lot of new two-dimensional materials have also been successfully synthesized,such as silicene,MoS₂ and so on.These materials show not only similar lattice structures,but also have common characteristics of band structures,the electrons have valley degree of freedom in addition to charge and spin.These new degrees of freedom of electrons provide more quantum resources for the carrying and processing of quantum information.In this paper,we study the properties of valley-and spin-polarization transport in silicene-based superlattice and superlattice of graphene/ferromagnetic silicene/graphene junction.The main contents are as follows:?1?We study valley-,spin-and pseudospin-polarization transport in silicene-based electrostatic potential,ferromagnetic and antiferromagnetic superlattice.The effect of ferromagnetic exchange field,antiferromagnetic exchange field and chemical potential on transport properties are analyzed and the role of electrostatic field in regulating valley-,spin-and pseudospin-polarization is discussed.The results indicate that when the number of lattice in the superlattice is more than 10,the valley-,spin-and pseudospin-polarization easy reach 100%in silicene-based superlattice and the direction of polarization can be reversed by adjusting electric field,which is helpful in manipulating degree of freedom of valley,spin and pseudospin in silicene superlattice.?2?In the case of finite ferromagnetic exchange field,we study the effect of electrostatic field and the length of ferromagnetic silicene region on valley-and spin-polarization transport in a superlattice of graphene/ferromagnetic silicene/graphene junction.The results indicate that valley-and spin-polarization can be easily reached by changing the length of center ferromagnetic silicene region and adjusting the electrostatic field,and fully valley-and spin-polarization can be reached by increasing the number of lattice.In a word,we obtain the condition for observing the fully valley and spin polarized current.