论文标题

扭曲双双层石墨烯的浮quet工程

Floquet engineering of twisted double bilayer graphene

论文作者

Rodriguez-Vega, Martin, Vogl, Michael, Fiete, Gregory A.

论文摘要

通过在分析和数值上研究的扭曲双重双层石墨烯(TDBG)样品的最新实验实现的动机,在自由空间中传播的圆极化光的影响,并局限于波导对这些系统的频带结构和拓扑特性的影响。这两个互补的Floquet协议使我们能够通过改变光的强度和频率来选择性调整系统的不同参数。对于自由空间中的驱动方案,在高频式方案中,我们发现在具有AB/BA堆叠的TDBG中,我们可以选择性地关闭一个山谷周围的区域中心的准偏度间隙,同时通过调谐驱动器的参数来增加对面的瓦莱附近的间隙。在带有AB/AB堆叠的TDBG中,对垂直静态电场的应用也可以获得类似的效果。此外,我们在不同的设置中研究驱动系统的拓扑特性,提供准确的有效浮力汉密尔顿人,并表明相对强大的驱动器可以产生平坦的频段。另一方面,纵向光限制在垂直于TDBG板的层跳跳的波导夫妇中,从而可以选择性地工程,而无需破坏静态系统的symmetries floquet Zone Center Center quasienergy频段的带宽。

Motivated by the recent experimental realization of twisted double bilayer graphene (TDBG) samples we study, both analytically and numerically, the effects of circularly polarized light propagating in free space and confined into a waveguide on the band structure and topological properties of these systems. These two complementary Floquet protocols allow us to selectively tune different parameters of the system by varying the intensity and the frequency of the light. For the drive protocol in free space, in the high-frequency regime, we find that in TDBG with AB/BA stacking, we can selectively close the zone-center quasienergy gaps around one valley while increasing the gaps near the opposite valley by tuning the parameters of the drive. In TDBG with AB/AB stacking, a similar effect can be obtained upon the application of a perpendicular static electric field. Furthermore, we study the topological properties of the driven system in different settings, provide accurate effective Floquet Hamiltonians, and show that relatively strong drives can generate flat bands. On the other hand, longitudinal light confined into a waveguide couples to the components of the interlayer hopping that are perpendicular to the TDBG sheet, allowing for selective engineering of the bandwidth of Floquet zone center quasienergy bands without breaking the symmetries of the static system.

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