The future electronic and spintronic devices will feature low power and small dimensions. Researchers have been studying on candidates of materials for such future devices. Recent progress in 2D materials (e.g., transition metal dichalcogenide (TMD)) have provided great promise for making new generation of nanoelectronics and spintronics because of their small thickness and attractive physical properties. This especially important to break through the limit of traditional silicon-CMOS technology that is driven by Moore’s Law based device scaling.
Observation of large quantum spin Hall Effect (QSHE) in TMD semimetal WTe2 at room temperature has been reported. The unique physical properties reveal that monolayer WTe2 can be an ideal topological insulator (TI) with non-dissipative conductive helical edge states that demonstrate spin-momentum locking.
In such a 2D quantum spin Hall Insulator (QSHI), the only scattering channel for the helical edge carriers is by back scattering. TI (topological insulator) is an insulator internally and a conductor along the edges. The electron transport along the edge possesses a unique characteristic, helicity, which indicates the electron rotation, spin, relies on the direction of electron movement. This characteristic makes QSHIs ideal for new spintronic devices. In classical electronic devices, physical signals are generated by the flow of electrons, or charges. In spintronic devices, the spin hall effect (SHE) converts the current formed by electron charge into the current based on electron spin. 2D topological insulators basically dissipate no energy while allow electrons to flow along the edge, which is the ideal materials for the next generation of ultra-low power devices.
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