Rashba effect

The spin transistor as represented in Fig. 34 is a vertical spin transistor. Figure 35 is a schematic picture of a lateral spin transistor as originally proposed by Datta and Das [179]. In this case, a iron emitter injects spins into a 2D electron gas. A Schottky gate can rotate the spin polarization by the Rashba effect, and another iron analyzer detects transmitted spin polarized current. 

Spin-orbit(SO) coupling is an important mechanism that influences the electron spin state [1], In low-dimensional structures Rashba SO interaction comes into play by introducing a potential to destroy the symmetry of space inversion in an arbitrary spatial direction [2-6], Then, based on the properties of Rashba effect, one can realize the controlling and manipulation of the spin in mesoscopic systems by external fields. Recently, Rashba interaction has been applied to some QD systems [6-8]. With the application of Rashba SO coupling to multi-QD structures, some interesting spin-dependent electron transport phenomena arise [7]. In this work, we study the electron transport properties in a three-terminal Aharonov-Bohm (AB) interferometer where the Rashba interaction is taken into account locally to a QD. It is found that Rashba interaction changes the quantum interference in a substantial way. 

Rashba-Step, J., Tatoyan, A., Duncan, R,. Ann, D., Pushpa-Rehka, T.R., and Sevanian, A, 1997, PhosphoUpid peroxidation induces cytosolic phospholipase A2 activity membrane effects versus enzyme phosphorylation, Arcii. Biochem. Biophys. 343 44-54. 

Summary. We consider the Josephson effect in a ballistic Superconductor/ Quantum Wire/ Superconductor junction. It is shown that the interplay of chiral symmetry breaking generated by Rashba spin-orbit interaction and Zeeman splitting results in the appearance of a Josephson current even in the absence of any phase difference between the superconductors. 

In quantum wires formed in a two-dimensional electron gas (2DEG) by lateral confinement the Rashba spin-orbit interaction is not reduced to a pure ID Hamiltonian H[s = asopxaz. As was shown in Ref. [4] the presence of an inplane confinement potential qualitatively modifies the energy spectrum of the ID electrons so that a dispersion asymmetry appears. As a result the chiral symmetry is broken in quantum wires with Rashba coupling. Although the effect was shown [4] not to be numerically large, the breakdown of symmetry leads to qualitatively novel predictions. 

We have considered here the influence of dispersion asymmetry and Zee-man splitting on the Josephson current through a superconductor/quantum wire/superconductor junction. We showed that the violation of chiral symmetry in a quantum wire results in qualitatively new effects in a weak superconductivity. In particularly, the interplay of Zeeman and Rashba interactions induces a Josephson current through the hybrid ID structure even in the absence of any phase difference between the superconductors. At low temperatures (T critical Josephson current. For a transparent junction with small or moderate dispersion asymmetry (characterized by the dimensionless parameter Aa = (vif — v2f)/(vif + V2f)) it appears, as a function of the Zeeman splitting Az, abruptly at Az hvp/L. In a low transparency (D Josephson current at special (resonance) conditions is of the order of yfD. In zero magnetic field the anomalous supercurrent disappears (as it should) since the spin-orbit interaction itself respects T-symmetry. However, the influence of the spin-orbit interaction on the critical Josephson current through a quasi-ID structure is still anomalous. Contrary to what holds... 

It has been shown that the spin-Hall effect may arise from various spin-orbit couphngs, such as a spin-orbit (SO) interaction induced by the electron-impurity scattering potential,a Rashba SO conphng in two-dimensional systems, etc. Murakami et al. also predicted a nonvanishing spin-Hall cnrrent (AHC) in a perfect Luttinger bnlk p -type semiconductors (no impurities or defects)." Experimental observations of the spin-Hall effect have been reported recently in a n -type bnlk semiconductor and in a two-dimensional heavy-hole system. ... 

In an attack on the particular problem of excitons which are weakly bound to localized "Impurities", Rashba and Gurgenishvill (2) derived the following relation between the oscillator strength of the bound exciton and the oscillator strength of the Intrinsic excitons f, using the effective-mass approximation... 

Here rp(k) is the momentum relaxation time which is due to the electron-phonon and electron-impurity scattering,stands for the electron distribution functions of spin a, h(k) is the DP term which serves as an effective magnetic field and is composed of the Dresselhaus term [10] due to the bulk inversion asymmetry (BIA) and the Rashba term [11] due to the structure inversion asymmetry (SIA),... 

In the presence of an in-plane electric field, electron spin can precess in the absence of any magnetic field at high temperature. This is understood that the inplane electric field induces a center-of-mass shift of the momentum which gives rise to an effective magnetic field proportional to the electric field [18]. The effect of strain on the spin R/D is also discussed and it is shown that one can effectively manipulate the spin R/D time by strain [29]. Cheng and Wu further discussed the spin R/D under identical Dresselhaus and Rashba terms [25]. A finite spin R/D time is obtained due to the cubic term in Eq. (2). 

Figure 1.13 Valence band structure of ZnO near the F point. The open circles represent the calculation results using the ASA-LMTO method including spin-orbit coupling. The solid lines are fits to the Rashba-Sheka-Pikus effective Hamiltonian. (After Ref [60].)...

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