Broken Symmetries and Kohn’s Theorem in Graphene Cyclotron Resonance
Broken Symmetries and Kohn’s Theorem in Graphene Cyclotron Resonance
复制标题
DOI：
10.1103/physrevx.10.041006
复制
发表时间：
2020-01
期刊：
影响因子：
--
通讯作者：
Jordan Pack;B. J. Russell;Yash Kapoor;J. Balgley;Jeff Ahlers;T. Taniguchi;Kenji Watanabe;E. Henriksen
中科院分区：
文献类型：
--
作者：
Jordan Pack;B. J. Russell;Yash Kapoor;J. Balgley;Jeff Ahlers;T. Taniguchi;Kenji Watanabe;E. Henriksen
通过红外透射磁谱研究了固定磁场下六方氮化硼包覆石墨烯中朗道能级跃迁的磁等离子体激元谱随填充因子的变化。由于最低的朗道能级占有率从半填充增加，观察到多个回旋共振峰的非单调进展，一个单峰演变成四个峰，并返回到两个，所有的线宽为0.5毫电子伏。这提供了一个新的窗口，在量子霍尔制度的电子相互作用与打破自旋和谷对称性的相互作用。峰值能量的分析表明，在费米能以下的自旋能隙的间接增强，在半填充时的狄拉克质量比最低的朗道能级完全充满时大近50%，以及小但明显的粒子-空穴不对称性。我们认为氮化硼在石墨烯回旋共振中能够观察到相互作用增强的对称性破缺中起着关键作用。
The magnetoplasmon spectrum of Landau level transitions in hexagonal boron nitride-encapsulated graphene is explored via infrared transmission magnetospectroscopy, as a function of the filling factor at fixed magnetic field. As the lowest Landau level occupancy is increased from half-filling, a non-monotonic progression of multiple cyclotron resonance peaks is observed, with a single peak evolving into four peaks and back to two, all with linewidths of order 0.5 meV. This provides a novel window on the interplay of electron interactions with broken spin and valley symmetries in the quantum Hall regime. Analysis of the peak energies shows an indirect enhancement of spin gaps below the Fermi energy, a Dirac mass at half-filling that is nearly 50\% larger than when the lowest Landau level is completely full, and a small but clear particle-hole asymmetry. We suggest a key role is played by the boron nitride in enabling interaction-enhanced broken symmetries to be observed in graphene cyclotron resonance.