A Study Of Spin Transport Properties Of ?A Topological Insulators

With the gradual miniaturization of electronic devices,the thermal power density of chips increases exponentially,and the heat dissipation problem of high integration of limited-size physical devices has become a major obstacle to the development of electronic devices.The use of topological insulators to replace traditional semiconductors,and the use of spin and energy valley degrees of freedom to replace charge as information carriers to design and fabricate transistors is an effective solution to the heat dissipation problem of nano-integrated circuits.Based on the non-equilibrium Green's function method,this paper studies the influence of external field induced edge state phase transition,valley polarization and energy band mismatch on ?A Topological Insulatorsspin spin transport and spin thermal transport.Based on the analysis of physical mechanism,all optically controlled transistors and multi-channel ferromagnetic germanene field effect transistors with great switching ratio are designed.Discuss the effective scheme of using energy valley polarization and external field structure to improve transistor breakdown voltage,switching ratio and lower threshold parameters.First,the influence of the Z-axis direction of the local exchange field and electric field to the spin-polarized electron transport properties Germanene nanoribbons are studied.The threshold exchange field strength required for the spin filtering effect is obtained.A method is proposed to effectively reduce the threshold exchange field strength required for the spin filtering effect with the assistance of an electric field.Secondly,we study the influence of circularly polarized light field and electric field on the spin-related thermoelectric effect of stanene nanoribbons.The results show that the properties and intensity of the thermoelectric current can be effectively controlled by the intensity and polarization direction of the circularly polarized light field.The relationship between the edge state phase transition of stanene and the light field,electric field is given,and the mechanism of thermoelectric current generation is clarified.Then,a novel ?A group topology single-layer material(silicene,germanene,stanene)transistor controlled by polarized light field is proposed.The results show that the edge state phase transition can be induced by polarized light,and the single-layer transistor effect of IVA topology can be realized by the mismatch of the energy bands between the receiving and non receiving regions.Finally,a multi-channel depletion-Type field effect transistor with vertical electric field action is proposed.The results show that the working state of the ferromagnetic germane field effect transistor can be realized by adjusting the electric field direction.The switching mechanism can be realized by the staggered potential of electric field and exchange field to induce edge state mismatch and spin blocking caused by energy valley mismatch.