Quantum engineering of Landau levels using isotopes in graphene-like graphite

Landau levels are cornerstones of a wide range of quantum phenomena and applications. Understanding the impact of the gauge field, or pseudomagnetic field, on the electronic structure of 2D materials is critical for manipulating Landau electrodynamics. Although extensive theoretical and experimental studies have been carried out to probe pseudomagnetic field in graphene, most of them have been focused on the strain- and substrate-engineering methods and magnetotransport properties. Here, we present using graphite as a unique material testbed for realizing isotope-induced pseudomagnetic field. Using magneto-Raman spectroscopy, we show that pure C12 graphite and C13-doped graphite both exhibit graphene-like Landau level transitions. Remarkably, we demonstrate that C13-doping leads to splitting of the Landau level transitions, a signature of pseudomagnetic field on the scale of 0.2 T. Moreover, the split Landau level transitions selectively couple with the G band phonon in distinct energy ranges. Our results highlight isotope doping as a feasible material engineering method of creating pseudomagnetic field and tuning magneto-optical properties in 2D quantum materials.朗道能级（Landau levels）是一系列量子现象与应用的基石。明晰规范场（gauge field）或称赝磁场（pseudomagnetic field）对二维（2D）材料电子结构的影响，对于调控朗道电动力学至关重要。尽管学界已开展大量理论与实验研究以探究石墨烯中的赝磁场，但绝大多数此类研究均聚焦于应变工程与衬底工程方法，以及磁输运性质。在此，我们提出以石墨作为实现同位素诱导赝磁场的独特材料测试平台。借助磁拉曼光谱（magneto-Raman spectroscopy）技术，我们发现纯碳12石墨与碳13掺杂石墨均展现出类石墨烯的朗道能级跃迁行为。值得注意的是，我们证实碳13掺杂会引发朗道能级跃迁的分裂，这一分裂现象可作为0.2特斯拉量级赝磁场的特征标识。此外，分裂后的朗道能级跃迁会在不同的能量范围内与G带声子发生选择性耦合。我们的研究结果表明，同位素掺杂是一种可行的材料工程手段，可用于在二维量子材料中构建赝磁场并调控其磁光性质。