Abstract:

We have measured the electron spin relaxation time in (111)-oriented GaAs quantum wells (QW) by time-resolved photoluminescence spectroscopy. By embedding the QWs in a PIN or NIP structure we demonstrate the tuning of the conduction band spin splitting and hence the spin relaxation time with an applied external electric field applied along the growth z direction.
The application of an external electric field of 50 kV/cm yields a two-order of magnitude increase of the spin relaxation time which can reach values larger than 30 ns; this is a consequence of the electric field tuning of the spin-orbit conduction band splitting which can almost vanish when the Rashba term compensates exactly the Dresselhaus one.
Experiments performed under transverse magnetic fields demonstrate that in addition to the spin lifetime, the spin coherence time can be significantly increased.
The role of the Dresselhaus cubic terms on both the temperature dependence of the effect and the anisotropy of the spin relaxation will be discussed. The tuning or suppression of the Dyakonov-Perel electron spin relaxation demonstrated here for GaAs/AlGaAs quantum wells is also possible in many other III-V and II-VI zinc-blende nanostructures since the principle relies only on symmetry considerations.
 
 
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