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Initiative II Highlights

Topological Insulators

Figure above shows the schematic of a TCI (SnTe) based transistor. The potential device resembles a standard FET, whereas here the TCI with contacts, sandwiched between two insulators (dielectrics), plays the role of the semiconductor.

Topological crystalline insulators (TCIs) are a new class of materials that exhibit an insulating bulk yet possess conducting states at the surface. The metallic character of the surface states relies on having a crystal symmetry (e.g. mirror symmetry) that prevents the surface from becoming insulating. In this collaborative theoretical study (with the group of Liang Fu, at MIT), it has been demonstrated that a small electric field can break this symmetry and turn the surface states into an insulating state. Since this electric field can be externally controlled, the device effectively works as a topological insulator transistor switch. This enables the charge and spin transport at the surface of TCIs to be controlled with high on/off ratio, fast operational speed and low energy consumption. This new approach may lead to the development of TCI based electronic and spintronic technology beyond the current CMOS technology.

Liu, J., Hsieh, T.H., Wei, P., Duan, W., Moodera, J.S., and Fu, L. “Spin-Filtered Edge States with an Electrically Tunable Gap in a Two-Dimensional Topological Crystalline Insulator.” Nature Materials. 13, 178-183 (2014)

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