Spin coherence in semiconductors: storage, transport and reduced dimensionality

We review the use of femtosecond-resolved optical techniques for the study of electron spin dynamics in semiconductors and show how these methods are able to address many of the issues that are centrally important to spin polarized semiconductor-based electronics. Pump–probe studies can be used to optimize spintronic material parameters, and have led to the observation of View the MathML source spin lifetimes in n-doped bulk GaAs and spin transport across macroscopic length scales View the MathML source. We have found that spin coherence is preserved across a semiconductor heterojunction over a broad range of temperatures, and can be protected by transport to regions of intrinsically lower decoherence. Studies of CdSe quantum dots ranging from 22 to 80 Å in diameter indicate that spin coherence in these structures is thermally robust, with nanosecond-scale spin lifetimes persisting to room temperature.