"Stacking" is a unique structural variation in two-dimensional layered materials, playing a crucial role in breaking symmetry and inducing various novel electrical, optical, magnetic, and topological phenomena.
To understand the influence of stacking structures on the physical properties of materials, a collaborative effort among multiple research teams from the Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, National Center for Nanoscience and Technology, and Shanghai Jiao Tong University recently conducted in-depth research on a significant stacking type called "ABC stacking" in trilayer graphene. They elucidated the strong coupling between electrons and infrared phonons in ABC-stacked trilayer graphene. The findings were published on February 29th in Nature Communications.
In recent years, trilayer graphene has attracted widespread attention among researchers. Typically, trilayer graphene can exhibit two different stacking geometries, including ABC stacking (also known as rhombohedral stacking) and ABA stacking (also known as Bernal stacking). These two stacking configurations of trilayer graphene possess completely different symmetries and electronic properties. For instance, trilayer graphene with centrosymmetric ABC stacking exhibits a tunable bandgap under a displacement electric field and can manifest a range of correlated physical effects not observed in ABA-stacked trilayer graphene, such as Mott insulating states, superconductivity, and ferromagnetism. Understanding these unique correlated physical effects in ABC-stacked trilayer graphene has become a frontier in current research.
Due to the electron-phonon coupling serving as the foundation for many novel physical phenomena and quantum phase transitions, exploring stacking-related electron-phonon coupling in trilayer graphene is of paramount importance for understanding the microscopic mechanisms of physical phenomena and designing novel device applications.
In experiments, researchers elucidated the strong coupling between electrons and infrared phonons in ABC-stacked trilayer graphene through gate-voltage-tunable Raman spectroscopy and excitation frequency-dependent near-field infrared spectroscopy. Moreover, by utilizing stacking-dependent electron-phonon coupling, they proposed a simple, non-destructive, highly efficient, and high spatial resolution imaging technique to identify the stacking order of graphene, laying a solid foundation for future research on multilayer graphene and twisted graphene.
Experts believe that the experimental results provide a new perspective for understanding novel correlated physical effects in ABC-stacked trilayer graphene, such as superconductivity and ferromagnetism.
Doctoral student Zan Xiaozhou from the Institute of Physics, Chinese Academy of Sciences, and Dr. Guo Xiangdong, Special Research Assistant from the National Center for Nanoscience and Technology, are the co-first authors of the paper. Professor Du Luojun and Professor Zhang Guangyu from the Institute of Physics, Chinese Academy of Sciences, and Dr. Dai Qing from the National Center for Nanoscience and Technology are the co-corresponding authors of the paper.
这是一个示意图，展示了三层石墨烯中堆叠相关的电声耦合。图的左半部分展示了ABA型三层石墨烯的堆叠，右半部分展示了ABC型三层石墨烯的堆叠。这张图由研究团队提供。
