Micro‐magneto‐Raman scattering spectroscopy is made use of to probe magneto‐phonon resonances (MPR) in suspended mono‐ to pentalayer graphene. MPR correspond to avoided crossings between zone‐center optical phonons (G‐mode) and optically active inter‐Landau level (LL) transitions and provide a tool to perform LL spectroscopy at a fixed energy (≈197 meV) set by the G‐mode phonon. Using a single‐particle effective bilayer model, the velocity parameter associated with each MPR is readily extracted. A single velocity parameter slightly above the bulk graphite value suffices to fit all MPR for N ≥ 2 layer systems. In contrast, in monolayer graphene, it is found that the velocity parameter increases significantly from (1.23 ± 0.01) × 10⁶ m s⁻¹ up to (1.45 ± 0.02) × 10⁶ m s⁻¹ as the first to third optically active inter‐LL transitions couple to the G‐mode phonon. This result is understood as a signature of enhanced many‐body effects in unscreened graphene.

中文翻译：

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通过磁声共振探究悬浮石墨烯的多体效应

微磁拉曼散射光谱用于探测悬浮的单层至五层石墨烯中的磁声子共振（MPR）。MPR对应于避免了区域中心光子（G模式）和光学活动的蓝涛能级（LL）跃迁之间的交叉，并提供了以G模式设定的固定能量（≈197meV）执行LL光谱的工具声子。使用单粒子有效双层模型，可以轻松提取与每个MPR相关的速度参数。对于N≥2 层系统，略高于本体石墨值的单个速度参数足以适合所有MPR 。相反，在单层石墨烯中，发现速度参数从（1.23±0.01）×10 ⁶  m s ^-1显着增加。当第一个至第三个光学有源LL间跃迁与G模式声子耦合时，最大（1.45±0.02）×10 ⁶  m s ^-1。该结果被认为是未经筛选的石墨烯增强了多体效应的标志。