Physics Department, Boston University, Boston, Massachusetts 02215, USA.
Phys Rev Lett. 2013 Apr 26;110(17):176603. doi: 10.1103/PhysRevLett.110.176603. Epub 2013 Apr 25.
Controlling the properties of materials by driving them out of equilibrium is an exciting prospect that has only recently begun to be explored. In this Letter we give a striking theoretical example of such materials design: a tunable gap in monolayer graphene is generated by exciting a particular optical phonon. We show that the system reaches a steady state whose transport properties are the same as if the system had a static electronic gap, controllable by the driving amplitude. Moreover, the steady state displays topological phenomena: there are chiral edge currents, which circulate a fractional charge e/2 per rotation cycle, with the frequency set by the optical phonon frequency.
通过使材料失去平衡来控制其性质是一个令人兴奋的前景，最近才开始探索。在这封信中，我们给出了一个这样的材料设计的惊人理论例子：通过激发特定的光学声子，在单层石墨烯中产生可调谐的能隙。我们表明，该系统达到了一个稳态，其输运性质与系统具有静态电子能隙相同，可通过驱动幅度进行控制。此外，稳态显示出拓扑现象：存在手性边缘电流，其每旋转一个周期就会循环一个分数电荷 e/2，其频率由光学声子频率设定。
