Stacking-dependent shear modes in trilayer graphene

Abstract

We observed distinct interlayer shear mode Raman spectra for trilayer graphene with ABA and ABC stacking order. There are two rigid-plane shear-mode phonon branches in trilayer graphene. We found that ABA trilayers exhibit pronounced Raman response from the high-frequency shear branch, without any noticeable response from the low-frequency branch. In contrast, ABC trilayers exhibit no response from the high-frequency shear branch, but significant Raman response from the low-frequency branch. Such complementary behaviors of Raman shear modes can be explained by the distinct symmetry of the two trilayer allotropes. The strong stacking-order dependence was not found in the layer-breathing modes, and thus represents a unique characteristic of the shear modes

Observation of interlayer phonon modes in van der Waals heterostructures

“…This is supported by the similar LBM observed in trilayer graphene with ABA and ABC stacking order [25].…”

“…In particular, it is intriguing to explore the possibility of generating new phonon modes through hybridization of different 2D crystals. Recent research [19][20][21][22][23][24][25][26][27][28][29][30][31] has revealed that interlayer interactions in few-layer graphene and TMDs can create a set of shear modes and layer-breathing modes (LBMs) that involve lateral and vertical displacement of individual layers, respectively. These interlayer phonon modes provide sensitive probes to layer thickness [19][20][21][22][23][24][25][26][27][28][29][30][31], stacking order [23][24][25]32] and surface adsorbates [26] of 2D materials.…”

Interlayer bond polarizability model for stacking-dependent low-frequency Raman scattering in layered materials

“…1 are roughly the same, according to experimental frequencies and firstprinciples calculations. 47,49 Therefore, the stacking effects on the frequencies and layer displacements in Eq. 11 and Eq.…”

“…7,9,33 They can be categorized into two types: in-plane shear and out-of-plane breathing vibration modes. Due to their greater sensitivity to interlayer coupling, LF Raman modes can directly probe the interfacial coupling, and they have been found as more effective indicators of the layer thickness [34][35][36][37][38][39][40][41][42][43][44][45][46] and stacking 24,[47][48][49][50][51][52][53][54][55] for diverse 2D materials. LF Raman spectroscopy is a rapidly developing field of research and has accelerated due to recent development of volume Bragg gratings for ultra-narrow optical filters with bandwidth about 1 cm -1 , which allows efficient cut-off of the excitation laser light without employing expensive triple monochromators for LF Raman measurements.…”

Stacking-Dependent Electronic Structure of Trilayer Graphene Resolved by Nanospot Angle-Resolved Photoemission Spectroscopy

“…[5][6][7][8][9] Moreover, they have different response under applied electric field. AAA stacking has the highest symmetry, and its electronic band structure consists of three equally displaced Dirac cones as shown in Fig.…”