Wang Can, Wang Kaili, Wang Huaiqiang, Tian Qichao, Zong Junyu, Qiu Xiaodong, Ren Wei, Wang Li, Li Fang-Sen, Zhang Wei-Bing, Zhang Haijun, Zhang Yi
Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering, School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 410114, China.
National Laboratory of Solid State Microstructure, School of Physics, Nanjing University, Nanjing 210093, China.
J Phys Chem Lett. 2023 Aug 17;14(32):7149-7156. doi: 10.1021/acs.jpclett.3c01271. Epub 2023 Aug 4.
Superlattice potentials imposed on graphene can alter its Dirac states, enabling the realization of various quantum phases. We report the experimental observation of a replica Dirac cone at the Brillouin zone center induced by a superlattice in heavily doped graphene with Gd intercalation using angle-resolved photoemission spectroscopy (ARPES). The replica Dirac cone arises from the (√3× √3)R30° superlattice formed by the intervalley coupling of two nonequivalent valleys (e.g., the Kekulé-like distortion phase), accompanied by a bandgap opening. According to the findings, the replica Dirac band in Gd-intercalated graphene disappears beyond a critical temperature of 30 K and can be suppressed by potassium adsorption. The modulation of the replica Dirac band is primarily attributable to the residual frozen gas, which can act as a source of intervalley scattering at temperatures below 30 K. Our results highlight the persistence of the hidden Kekulé-like phase within the heavily doped graphene, enriching our current understanding of its replica Dirac Fermions.
施加在石墨烯上的超晶格势可以改变其狄拉克态，从而实现各种量子相。我们报告了使用角分辨光电子能谱（ARPES）在通过插入钆实现重掺杂的石墨烯中，由超晶格在布里渊区中心诱导出的复制狄拉克锥的实验观测结果。该复制狄拉克锥源自由两个不等价谷的谷间耦合形成的（√3×√3）R30°超晶格（例如，类凯库勒畸变相），同时伴随着带隙的打开。根据这些发现，插入钆的石墨烯中的复制狄拉克带在超过30 K的临界温度时消失，并且可以通过钾吸附来抑制。复制狄拉克带的调制主要归因于残余的冻结气体，其在低于30 K的温度下可作为谷间散射的来源。我们的结果突出了重掺杂石墨烯中隐藏的类凯库勒相的持续性，丰富了我们目前对其复制狄拉克费米子的理解。
