Physics and applications of zero-magnetic-field spin splitting in semiconductor nano-structures

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In this project, we have investigated electron spin-precession spatial spin-coherence s in (001) quantum wells. Effects of nuclear spins on the spin precession have also been investigated.Results of Monte Carlo simulation, it has been clarified that shape of electrodes is important for sufficient spin coherence length. When the Rashba effective magnetic field is much larger than the Dresselhaus one, circular or Corbino electrodes are quite effective, because the effective field is perpendicular to the electron wave vector and the strength in proportional the length of it. On the other hand, when the Rashba and the Dresselhaus field are comparable, usual parallel electrodes are appropriate, but the electric current should along (110) or equivalent direction. Using these types of electrodes, we can get spin coherence length sufficient for device applicationsEffects of nuclear spin-polarization induced by electron spin-polarization is passively affects the electron spin-precession. We have investigated this effect also by Monte Carlo simulation. Nuclear spins are polarized in few seconds and induces magnetic field sufficient to affects the electron spin-precession. This induced field degrades strongly the electron spin-polarization. Thus, it is important for device application to develop some method to overcome this problem.