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Ultrafast generation of pseudo-magnetic field for valley excitons in WSe₂ monolayers
Ist Teil von
Science (American Association for the Advancement of Science), 2014-12, Vol.346 (6214), p.1205-1208
Ort / Verlag
United States: The American Association for the Advancement of Science
Erscheinungsjahr
2014
Quelle
Science Online科学在线
Beschreibungen/Notizen
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.