Identification of graphite with perfect rhombohedral stacking by electronic Raman scattering

Pálinkás, András and Márity, Krisztián and Kandrai, Konrád and Tajkov, Zoltán and Gmitra, Martin and Vancsó, Péter and Tapasztó, Levente and Nemes Incze, Péter (2024) Identification of graphite with perfect rhombohedral stacking by electronic Raman scattering. CARBON, 230. No.-119608. ISSN 0008-6223

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Abstract

Rhombohedral graphite (RG) shows strong correlations in its topological flat band and is pivotal for exploring emergent, correlated electronic phenomena. One key advantage is the enhancement of electronic interactions with the increase in the number of rhombohedrally stacked graphene layers. Increasing thickness also leads to an exponential increase in the number of stacking configurations, necessitating a precise method to identify flawless rhombohedral stackings. Overcoming this challenge is difficult because the established technique for stacking sequence identification, based on phonon originated Raman processes (e.g. the 2D peak), fails in thick RG samples. We demonstrate that the strong layer dependence of the band structure can be harnessed to identify RG without stacking faults. For thicknesses ranging from 3 to 12 layers, we show that each perfect RG structure presents distinctive peak positions in electronic Raman scattering (ERS), directly fingerprinting the flawless stacking. This measurement can be carried out using a conventional confocal Raman spectrometer at room temperature, using visible excitation wavelengths. Consequently, this overcomes the identification challenge by providing a simple and fast optical measurement technique, thereby helping to establish RG as a platform for studying strong correlations in one of the simplest crystals possible.

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