Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China.
Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité , 24 rue Lhomond, 75231 Paris Cedex 05, France.
Nano Lett. 2016 Apr 13;16(4):2387-92. doi: 10.1021/acs.nanolett.5b05161. Epub 2016 Mar 9.
Graphene placed on hexagonal boron nitride (h-BN) has received a wide range of interest due to the improved electrical performance and rich physics from the interface, especially the emergence of superlattice Dirac points as well as Hofstadter butterfly in high magnetic field. Instead of transferring graphene onto h-BN, epitaxial growth of graphene directly on a single-crystal h-BN provides an alternative and promising way to study these interesting superlattice effects due to their precise lattice alignment. Here we report an electrical transport study on epitaxial graphene superlattice on h-BN with a period of ∼15.6 nm. The epitaxial graphene superlattice is clean, intrinsic, and of high quality with a carrier mobility of ∼27 000 cm(2) V(-1) s(-1), which enables the observation of Hofstadter butterfly features originated from the superlattice at a magnetic field as low as 6.4 T. A metal-insulator transition and magnetic field dependent Fermi velocity were also observed, suggesting prominent electron-electron interaction-induced many-body effects.
由于界面改善了电学性能和丰富的物理性质，特别是在强磁场中出现超晶格狄拉克点和霍夫施塔特蝴蝶，石墨烯置于六方氮化硼（h-BN）上受到了广泛关注。取代将石墨烯转移到 h-BN 上，直接在单晶 h-BN 上外延生长石墨烯提供了一种替代且有前途的方法来研究这些有趣的超晶格效应，因为它们具有精确的晶格对准。在这里，我们报告了具有约 15.6nm 周期的 h-BN 上外延石墨烯超晶格的电输运研究。外延石墨烯超晶格是清洁的、本征的和高质量的，载流子迁移率约为 27000cm^2V^-1s^-1，这使得能够在低至 6.4T 的磁场中观察到源自超晶格的霍夫施塔特蝴蝶特征。还观察到金属-绝缘体转变和磁场依赖的费米速度，这表明存在突出的电子-电子相互作用诱导的多体效应。
