Symmetry breaking and fractionalization beyond the zero Landau level of graphene

石墨烯零朗道能级之外的对称性破缺和分馏

• 批准号: 518372354
• 负责人: Professor Dr. Inti Sodemann Villadiego
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/518372354?language=en
• 关键词: Symmetry; breaking; fractionalization; beyond; zero

In the presence of perpendicular magnetic fields graphene displays a fascinatingly rich set of states in the quantum Hall regime, featuring an intricate interplay of symmetry breaking, topology and fractionalization of its valley and spin degrees of freedom. Despite our substantial progress in understanding these states many puzzles and un-explored directions remain. For example, in the zero Landau level recent STM experiments have revealed valence bond solid and charge density wave states under the conditions where earlier experiments reported evidence for anti-ferromagnets. Experiments in higher Landau levels have displayed many other puzzles, such as the presence of bubble states in the second Landau level but with no concomitant evidence of stripes states. And, amazingly, also evidence of even denominator fractional quantum Hall states near partial half-filling of the third Landau level. The precise nature of these states and their valley/spin order remains to be understood. Because of its exposed character graphene offers to us an unprecedented opportunity to directly image these states with local probes. Additionally bilayer graphene offers to us a remarkable opportunity to realize a dramatically new class of integer and fractional quantum Hall states without inversion symmetry that have never been realized experimentally before. This arises because of its near degeneracy of orbitals with N=0 and N=1 cyclotron character. Our project aims to develop the theory of these states in monolayer and bilayer graphene and on understanding their physical properties that can aid their experimental realization and detection.

在垂直磁场的存在下，石墨烯在量子霍尔机制中显示出一组迷人的丰富状态，具有对称性破缺，拓扑结构及其谷和自旋自由度的分形的复杂相互作用。尽管我们在理解这些状态方面取得了实质性的进展，但仍然存在许多难题和未探索的方向。例如，在零朗道水平最近的STM实验揭示了价键固体和电荷密度波状态下的条件下，早期的实验报告的证据反铁磁体。在更高的朗道能级上的实验还显示了许多其他的谜题，比如在第二个朗道能级上存在气泡态，但没有伴随的条纹态的证据。而且，令人惊讶的是，也有证据表明，在第三朗道能级的部分半填充附近，存在偶数分母分数量子霍尔态。这些状态的确切性质及其谷/自旋顺序仍有待理解。由于其暴露的特性，石墨烯为我们提供了一个前所未有的机会，用局部探针直接成像这些状态。此外，双层石墨烯为我们提供了一个显着的机会，以实现一个显着的新的类的整数和分数量子霍尔态没有反演对称性，从来没有实现过实验。这是因为它的N=0和N=1回旋特征轨道的近简并性。我们的项目旨在发展单层和双层石墨烯中这些状态的理论，并了解它们的物理性质，以帮助它们的实验实现和检测。