Confirmation of Mesoscopic Spin Transport in InGaAs Quantum Wells

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For InP-lattice-matched InGaAs quantum wells, we have quantitatively revealed the zero-field spin splitting term. Not only in showing the presence of the Rashba term for the first time which has been the target of controversy for long time, but also we have succeeded in elucidating its size quantitatively. More specifically, we have shown for the first time the linear relation between the Rashba coefficient alpha and the electric field inside the well <Ez> from the theoretical analysis of the weak antilocalization effect that is seen in the magneto-conductivity data at dilution temperatures. In addition, we have found that the Dresselhaus term in this system is very small. Finally, we have also measured the time-reversal quantum interference effect in a mesoscopic loop array structure that is fabricated in a wafer whose <Ez> can be varied across zero by gate and demonstrated the effectiveness of the semi-classical approach in theory.