论文标题
双层石墨烯中的超快谷极化
Ultrafast valley polarization in bilayer graphene
论文作者
论文摘要
我们研究双层石墨烯与单个振荡的圆形超快光脉冲的理论上相互作用。脉冲的正常成分破坏了系统的反转对称性，并打开了动态的带隙，因此，传导带的山谷选择性种群对脉冲入射角变得敏感。我们表明，山谷极化的大小可以通过手性光学脉冲的入射角，振幅和平面极化角度控制。随后，可以使用线性极化的飞秒长脉冲的圆形极化脉冲序列来控制由前面脉冲产生的山谷极化。通常，线性极化的脉冲使系统去极化。这种去极化的大小取决于振幅，以及线性极化脉冲的平面偏振角。我们的协议为ValleyTronics应用程序提供了一个有利的平台。
We study theoretically interaction of a bilayer graphene with a circularly polarized ultrafast optical pulse of a single oscillation at an oblique incidence. The normal component of the pulse breaks the inversion symmetry of the system and opens up a dynamical band-gap, due to which a valley-selective population of the conduction band becomes sensitive to the angle of incident of the pulse. We show that the magnitude of the valley polarization can be controlled by the angle of incidence, the amplitude, and the angle of in-plane polarization of the chiral optical pulse. Subsequently, a sequence of a circularly polarized pulse followed by a linearly polarized femtosecond-long pulse can be used to control the valley polarization created by the preceding pulse. Generally, the linearly polarized pulse depolarizes the system. The magnitude of such a depolarization depends on the amplitude, and the in-plane polarization angle of the linearly polarized pulse. Our protocol provides a favorable platform for applications in valleytronics.
