在 WSe₂ 单层中超快产生赝磁场用于谷激子。
Ultrafast generation of pseudo-magnetic field for valley excitons in WSe₂ monolayers.
机构信息
Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA.
Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA. Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
出版信息
Science. 2014 Dec 5;346(6214):1205-8. doi: 10.1126/science.1258122.
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.
谷自由度是在原子层薄的二维过渡金属二卤化物（MX2）中出现的一种自由度。类比于自旋电子学中对自旋的控制，操控它的能力可以开辟令人兴奋的机会。在这里，我们证明了可以通过使用圆偏振飞秒脉冲来产生超快和超高谷赝磁场，从而选择性地控制单层 MX2 中的谷自由度。使用超快泵浦探测光谱学，我们从非共振泵浦中观察到 WSe2 单层中的纯谷选择光学斯塔克效应，导致 K 和 K'谷激子跃迁之间的能量分裂超过 10 毫电子伏特。我们的研究为量子信息应用中相干地操控谷极化开辟了可能性。
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