Spin Control

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Science  23 Sep 2011:
Vol. 333, Issue 6050, pp. 1680
DOI: 10.1126/science.333.6050.1680-a

Unlike regular electronic circuitry, spintronic devices foster current based on the electron's spin, leading to much higher efficiencies as a consequence of reduced heat loss. However, spintronics is not yet ready to hit the shelves, mainly because manipulating spin is difficult and often requires very low temperatures. A crucial ingredient is the electric control of spin, achievable through spin-orbit interaction (SOI), which couples the electron's motion to its spin. One candidate for this control is a type of SOI called the Rashba effect, which leads to an energy splitting of electronic states with opposite spins—the bigger the splitting, the better. King et al. use angle-resolved photoemission spectroscopy (ARPES) to observe a very large Rashba spin-splitting effect in the material Bi2Se3, which has lately attracted attention as a promising topological insulator. The authors find that the residual adsorbates on the material surface affect the band structure, creating a quantum well, which hosts a two-dimensional electron gas (2DEG). When the concentration of these adsorbates is controllably varied, the amount of spin splitting in the 2DEG varies too: The Rashba effect is not only large, it is also tunable. Because electric gating would be expected to have the same tuning effect, which persists to room temperature, this material holds potential for realistic spintronic applications.

Phys. Rev. Lett. 107, 96802 (2011).

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