Winterer Felix, Seiler Anna M, Ghazaryan Areg, Geisenhof Fabian R, Watanabe Kenji, Taniguchi Takashi, Serbyn Maksym, Weitz R Thomas
Physics of Nanosystems, Department of Physics, Ludwig-Maximilians-Universität München, Amalienstrasse 54, Munich 80799, Germany.
1st Physical Institute, Faculty of Physics, University of Göttingen, Friedrich-Hund-Platz 1, Göttingen 37077, Germany.
Nano Lett. 2022 Apr 27;22(8):3317-3322. doi: 10.1021/acs.nanolett.2c00435. Epub 2022 Apr 11.
Bernal-stacked multilayer graphene is a versatile platform to explore quantum transport phenomena and interaction physics due to its exceptional tunability via electrostatic gating. For instance, upon applying a perpendicular electric field, its band structure exhibits several off-center Dirac points (so-called Dirac gullies) in each valley. Here, the formation of Dirac gullies and the interaction-induced breakdown of gully coherence is explored via magnetotransport measurements in high-quality Bernal-stacked (ABA) trilayer graphene. At zero magnetic field, multiple Lifshitz transitions indicating the formation of Dirac gullies are identified. In the quantum Hall regime, the emergence of Dirac gullies is evident as an increase in Landau level degeneracy. When tuning both electric and magnetic fields, electron-electron interactions can be controllably enhanced until, beyond critical electric and magnetic fields, the gully degeneracy is eventually lifted. The arising correlated ground state is consistent with a previously predicted nematic phase that spontaneously breaks the rotational gully symmetry.
伯纳尔堆叠的多层石墨烯是一个探索量子输运现象和相互作用物理的通用平台，这是由于其通过静电门控具有出色的可调性。例如，施加垂直电场时，其能带结构在每个谷中会出现几个偏心狄拉克点（所谓的狄拉克沟）。在此，通过高质量伯纳尔堆叠（ABA）三层石墨烯中的磁输运测量，研究了狄拉克沟的形成以及相互作用诱导的沟相干性破坏。在零磁场下，识别出多个表明狄拉克沟形成的里夫希茨转变。在量子霍尔 regime 中（此处原文 regime 未明确中文释义，可保留英文），狄拉克沟的出现表现为朗道能级简并度的增加。当同时调节电场和磁场时，电子-电子相互作用可以可控地增强，直到超过临界电场和磁场，沟简并最终被解除。所产生的关联基态与先前预测的自发打破旋转沟对称性的向列相一致。
