Garcia-Pomar J L, Cortijo A, Nieto-Vesperinas M
Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, Madrid, Spain.
Phys Rev Lett. 2008 Jun 13;100(23):236801. doi: 10.1103/PhysRevLett.100.236801. Epub 2008 Jun 10.
We propose a device to break the valley degeneracy in graphene and produce fully valley-polarized currents that can be either split or collimated to a high degree in a experimentally controllable way. The proposal combines two recent seminal ideas: negative refraction and the concept of valleytronics in graphene. The key new ingredient lies in the use of the specular shape of the Fermi surface of the two valleys when a high electronic density is induced by a gate voltage (trigonal warping). By changing the gate voltage in a n-p-n junction of a graphene transistor, the device can be used as a valley beam splitter, where each of the beams belong to a different valley, or as a collimator. The result is demonstrated through an optical analogy with two-dimensional photonic crystals.
我们提出了一种装置，用于打破石墨烯中的能谷简并性，并产生完全谷极化电流，该电流可以通过实验可控的方式进行高度分裂或准直。该提议结合了两个近期的开创性想法：负折射和石墨烯中的谷电子学概念。关键的新要素在于，当通过栅极电压（三角翘曲）诱导出高电子密度时，利用两个能谷的费米面的镜面形状。通过改变石墨烯晶体管n-p-n结中的栅极电压，该装置可以用作谷分束器，其中每个光束属于不同的能谷，也可以用作准直器。通过与二维光子晶体的光学类比来证明这一结果。
