Related Nature Of Spin Transport In Spin-orbit Coupling Two-dimensional Electron Gas

Spintronics has become a fast developing area using the electron spin degrees of freedom,rather than the conventional electron charge in electronic devices.Spin-orbit Coupling(SOC) is the crucial physical mechanism,which influences the usual semiconductor materials in both spin control and relaxation.Thus SOC is the conceivable factor which is worthy to be taken into account in the applications of semiconductor spintronics devices.Recently,SOC in semiconductor has attracted many scientists attention in the world,and many important developments have been obtained,such as intrinsic Spin Hall Effect(ISHE).These researches provide new avenue for the generation of spin current in the semiconductors,and afford the physical basis for the spin electronics devices which are fully controlled by electric field in the future.In Chapter one,based on the summarization of the spintronics development trend, we first introduce the two kinds of spin-orbit coupling in two-dimensional electron systems simply,including Rashba SOC and Dresselhaus SOC.In addition,we also introduce the spin Hall effect(SHE) which is induced by the spin-orbit coupling.According to the different explanation,SHE can be divided into intrinsic SHE(ISHE) and extrinsic SHE(ESHE).Subsequently,we continue to introduce the characters of transport electrons in two-dimensional electron gas,including spin current,spin polarization, spin accumulation,as well as the impact of impurity or defect to these characters.Besides, we also introduce the present experimental evolvement about the SHE.At last, the main content and meaning of this paper are illustrated.In Chapter two,based on the simple introduction about the spin helix,for a two-dimensional electron gas with equal Rashba and Dresselhaus spin-orbit coupling strength(ReD model),and the Dresselhaus[110]model,the influence of an external magnetic field on the lifetime of the Spin Helix(SH) has been considered.In Chapter three,in terms of Kubo's formula and Green's function method,we study the spin polarization due to the effect from magnetic impurities with anisotropic spin dependent delta type coupling to electrons when an external dc electric field in plane is applied.The vertex correction of impurities in ladder approximation is carried out.We find that the strength of spin polarization can be significantly modified by vertex correction and the spin polarization is relevant to the anisotropy coefficient,but the direction of spin polarization can not be changed.In Chapter four,making use of the Kubo's linear response theory,we discuss the anomalous Hall Effect(AHE) in a two-dimensional electron gas(2DEG) with Rashba SOC subjected to a homogeneous out-of-plane magnetization,by taking into account the coupling between the nonmagnetic impurities,anisotropic magnetic impurities and the itinerant electrons,respectively.We found that the anomalous Hall conductivity is nonvanishing and is correlative to the anisotropy coefficient,which is different from the nonmagnetic impurities conditions.