Rhombohedral stacking-faults in exfoliated highly oriented pyrolytic graphite
Filippo Boi,
Cheng-Yang Lee,
Shanling Wang,
Hansong Wu,
Lei Li,
Lin Zhang,
Jiaxin Song,
Yixin Dai,
Ayoub Taallah,
Omololu Odunmbaku,
Anna Corrias,
Aleksandra Baron-Wiechec,
Shuping Zheng,
Salvatore Grasso
Affiliations
Filippo Boi
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China; Corresponding author.
Cheng-Yang Lee
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Shanling Wang
Analytical & Testing Center, Sichuan University, Chengdu, China
Hansong Wu
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Lei Li
Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, China
Lin Zhang
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Jiaxin Song
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Yixin Dai
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Ayoub Taallah
College of Physics, Condensed Matter Group, Sichuan University, Chengdu, China
Omololu Odunmbaku
MOE Key Laboratory of Low-grade Energy Utilization Technologies and Systems, CQU-NUS Renewable Energy Materials & Devices Joint Laboratory, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
Anna Corrias
School of Chemistry and Forensic Science, University of Kent, Canterbury, UK
Aleksandra Baron-Wiechec
Guangdong Technion-Israel Institute of Technology (GTIT), Shantou, China
Shuping Zheng
Analytical & Testing Center, Sichuan University, Chengdu, China
Salvatore Grasso
Queen Mary University of London, School of Engineering and Materials Science, UK; Corresponding author.
The recent observation of possible granular superconductivity in highly oriented pyrolytic graphite (HOPG) has attracted significant research interest. Here we report a novel investigation on the structural-properties of exfoliated-HOPG. We investigated two types of exfoliation methods, involving either a full (method-1) or partial (method-2) contact between adhesive tape and the main HOPG. Structural characterization was obtained by employing X-ray diffraction (XRD), Raman spectroscopy and electron microscopy (SEM). In particular, Raman point and mapping spectroscopy revealed significant structural-transitions from ABA (Bernal) to ABC (rhombohedral) stacking (stacking-faults), in those samples obtained with the method-2. Interestingly, strained regions exhibiting structural-deformations with a ridge-like morphology were reproducibly identified. The acquired Raman-spectra revealed a local enhancement of the D and D’ bands-intensity together with contributions arising from Electronic Raman Scattering (ERS) across the band-gap of rhombohedral-graphite, at middle (∼1870 cm−1) and high (∼ 2680 cm−1) frequency. HRTEM of the samples produced with the method-2 allowed also for the identification of local-coexistence of ripplocation-like defects with moiré superlattices, an indicator of non-uniform c-axis configuration.
