Ultrafast generation of pseudo-magnetic field for valley excitons in WSe₂ monolayers

The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultra...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2014-12, Vol.346 (6214), p.1205-1208
Main Authors: Kim, Jonghwan, Hong, Xiaoping, Jin, Chenhao, Shi, Su-Fei, Chang, Chih-Yuan S, Chiu, Ming-Hui, Li, Lain-Jong, Wang, Feng
Format: Article
Language:English
Subjects:
Electrons
Freedom
Information Processing
Magnetic fields
Metal oxides
Quantum physics
Online Access:Get full text
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Summary:The valley pseudospin is a degree of freedom that emerges in atomically thin two-dimensional transition metal dichalcogenides (MX2). The capability to manipulate it, in analogy to the control of spin in spintronics, can open up exciting opportunities. Here, we demonstrate that an ultrafast and ultrahigh valley pseudo-magnetic field can be generated by using circularly polarized femtosecond pulses to selectively control the valley degree of freedom in monolayer MX2. Using ultrafast pump-probe spectroscopy, we observed a pure and valley-selective optical Stark effect in WSe2 monolayers from the nonresonant pump, resulting in an energy splitting of more than 10 milli-electron volts between the K and K' valley exciton transitions. Our study opens up the possibility to coherently manipulate the valley polarization for quantum information applications.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1258122