Study On The Properties Of Spin Transport In Silylene And Stanene Nanoribbons

In recent years,hexagonal honeycomb structure materials,especially hexag-onal honeycomb structure with buckled structure,have been widely studied?Its superior physical properties have been gradually excavated.The transport prop-erties of two kinds of hexagonal honeycomb structures are investigated by using the tight-binding model and the Green's function method.The first type of hexag-onal honcycoml)structure is silicene,and we propose two types of nonsymmetric T-shaped silicene nanoribbons that show peculiar spin transport properties.In type ? and ? T-shaped silicene nanoribbons,we modulate the overall conductance to one lead by changing the size of another lead.Considering the exchange field,the nearly perfect spin polarization can be easily obtained in the structure of the semiconductor T-type silicene nanoribbons.In addition,the spin polarization of each lead can be controlled by adjusting the size of the T-shaped terminals,the electric field and the exchange field.Another hexagonal honeycomb structure material is stanene.We investigate the related electronic structure and transport properties of tin nanoribbons.Here we divide the scattering region of tin nanoribbons into two equal subsca.ttering regions along the width direction.Firstly,by adjusting the direction and value of the antiferromagnetic exchange field in the two subscattering regions,which are impacted to the two different atoms in tin nanoribbons,we can realize the nearly perfect spin polarization with the perpendicular electric field.Then,ferro-magnetie and antiferromagnetic exchange fields(hybrid exchange field)are added into the two subscattering regions,respectively.When the adjacent tin atoms of the two subscattering regions have the same direction acted by exchange field,because of the splitting of the valley,although the size of the exchange field of the two subscattering regions can control the polarization of the edge state spins,it is possible to achieve almost perfect spin polarization without considering the effect of vertical electrie field.When the direction of the adjacent atoms in the scattering region are opposite,at,this time,the width of the nearly perfect spin polarization with energy is different due to the different degree both the valley and the spin splitting.Since these two kinds of hexagonal honeycomb structures exhibit special spin transmission properties,both of them can be considered as important components of spin polarized nanodevices and nanoelectronic circuits.