Valleytronics

 ( Quantum Mechanics ) 

Valleytronics (from valley and electronics) is an experimental area in that exploits local extrema ("valleys") in the electronic band structure. Certain have multiple "valleys" in the electronic band structure of the first Brillouin zone, and are known as multivalley semiconductors. Valleytronics is the technology of control over the valley degree of freedom, a local optimum on the valence band/conduction band, of such multivalley semiconductors.

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Details The term was coined in analogy to spintronics. While in spintronics the internal degree of freedom of spin is harnessed to store, manipulate and read out bits of information, the proposal for valleytronics is to perform similar tasks using the multiple extrema of the band structure, so that the information of 0s and 1s would be stored as different discrete values of the crystal momentum.

Valleytronics may refer to other forms of quantum manipulation of valleys in semiconductors, including quantum computation with valley-based qubits,"Universal quantum computing with spin and valley states". Niklas Rohling and Guido Burkard. New J. Phys. 14, 083008(2012)."A valley–spin qubit in a carbon nanotube". E. A. Laird, F. Pei & L. P. Kouwenhoven. Nature Nanotechnology 8, 565–568 (2013). valley blockade and other forms of quantum electronics. First experimental evidence of valley blockade predicted in Ref. (which completes the set of Coulomb blockade and Pauli spin blockade) has been observed in a single atom doped silicon transistor.

Several theoretical proposals and experiments were performed in a variety of systems, such as graphene, few-layer phosphorene, some transition metal dichalcogenide monolayers,"Valley polarization in MoS2 monolayers by optical pumping". Hualing Zeng, Junfeng Dai, Wang Yao, Di Xiao and Xiaodong Cui. Nature Nanotechnology 7, 490–493 (2012). diamond,"Generation, transport and detection of valley-polarized electrons in diamond". Jan Isberg, Markus Gabrysch, Johan Hammersberg, Saman Majdi, Kiran Kumar Kovi and Daniel J. Twitchen. Nature Materials 12, 760–764 (2013). bismuth,"Field-induced polarization of Dirac valleys in bismuth". Zengwei Zhu, Aurélie Collaudin, Benoît Fauqué, Woun Kang and Kamran Behnia. Nature Physics 8, 89-94 (2011). silicon, carbon nanotubes, aluminium arsenide"AlAs two-dimensional electrons in an antidot lattice: Electron pinball with elliptical Fermi contours". O. Gunawan, E. P. De Poortere, and M. Shayegan. Phys. Rev. B 75, 081304(R)(2007). and silicene."Spin valleytronics in silicene: Quantum spin Hall–quantum anomalous Hall insulators and single-valley semimetals". Motohiko Ezawa, Phys. Rev. B 87, 155415 (2013)

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External links

• Matthew Francis: "Experiments hint at a new type of electronics: valleytronics" at Ars Technica
• Source of the above: Zeng, H., Dai, J., Yao, W., et al. "Valley polarization in MoS₂ monolayers by optical pumping". Nature Nanotechnology, 7 490–493 (August 2012). .

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