Direct mapping of the formation of a persistent spin helix

  title={Direct mapping of the formation of a persistent spin helix},
  author={Manuel Walser and Christian Reichl and Werner Wegscheider and G. Salis},
  journal={Nature Physics},
Spin–orbit interaction induces spin-polarization decay in semiconductor quantum wells. But this decay can be suppressed in favour of a helical spin mode by tuning the interaction. Optical pump–probe measurements provide direct evidence of the resulting helix—a signature that has so far only been inferred from transport measurements. 

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