Sending Spins Through Rough Terrain

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Science  18 Feb 2000:
Vol. 287, Issue 5456, pp. 1169
DOI: 10.1126/science.287.5456.1169b

Conventional electronics uses charges to switch currents on and off. In magnetoelectronics, or spintronics, the quantum-mechanical properties of the charge carriers (electron spin) are utilized as the pieces of information transferred around the system, but this has been restricted so far to studies of homogeneous systems. One of the major problems for an integrated magnetoelectronics technology is the transfer of the spin-states between different types of materials, that is, across heterojunctions. The different environments for the electrons in each of the layers can cause decoherence of the electron spin and prevent a coherent signal from crossing over.

Using a GaAs/ZnSe heterostructure, Malajovich et al. show that optically induced spins can be transferred from the GaAs layer across the interface and into the adjacent ZnSe layer without loss of coherence, despite an almost two-fold difference in band gap and different g factors describing the electron environment of the layers. Although the fraction of spins making it across the layers is relatively small (perhaps between 2.5 and 10% of those induced in the GaAs layer), the robustness of the spins described in this work provides encouragement for further development of spintronic devices.—ISO

Phys. Rev. Lett.84, 1015 (2000).

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