Symmetry and Spin Dephasing in (110)-Grown Quantum Wells

Symmetry and spin dephasing in (110)-grown GaAs quantum wells (QWs) are investigated applying magnetic field induced photogalvanic effect and time-resolved Kerr rotation. We show that magnetic field induced photogalvanic effect provides a tool to probe the symmetry of (110)-grown quantum wells. The photocurrent is only observed for asymmetric structures but vanishes for symmetric QWs. Applying Kerr rotation we prove that in the latter case the spin relaxation time is maximal; therefore, these structures set the upper limit of spin dephasing in GaAs QWs. We also demonstrate that structure inversion asymmetry can be controllably tuned to zero by variation of $\delta$-doping layer positions.

Figure 1

Band profile of QWs and doping position.

Figure 2

Magnetic field dependences of $J_x^{\mathrm{MPGE}}$ for the radiation polarized along $x$ and an in-plane magnetic field ($\mathit{B}\parallel y$).

Figure 3

Magnetic field dependences of $J_x^{\mathrm{MPGE}}$ for sample E measured for the radiation polarized along $x$ and a magnetic field perpendicular to the QWs.

Figure 4

Kerr rotation measured in asymmetrically grown QWs samples B C, D and symmetrical structure E. We note that the fast decaying components in the TRKR signals at short times are due to spin relaxation of photoexcited holes.