标题： 通过兰道能级光谱检测由应变和带电缺陷散射产生的石墨烯单层中的巨大电子-空穴不对称性 显示英文标题

标题： Detecting giant electron-hole asymmetry in graphene monolayer generated by strain and charged-defect scattering via Landau level spectroscopy

摘要： 石墨烯单层中的电子-空穴对称性，类似于宇宙中电子和正电子之间的固有对称结构，在无质量狄拉克费米子的手性和手性隧穿中起着关键作用。 在这里，我们证明应变和带电缺陷散射都可能在石墨烯单层中显著破坏这种对称性。 在我们的实验中，通过朗道能级光谱直接测量了电子和空穴的费米速度。 在具有晶格变形和曲率的应变石墨烯中，和分别测量为1.2 x 106 m/s和1.02 x106 m/s。 这种巨大的不对称性来源于应变区域中次近邻跃迁的增强。 在正电荷缺陷周围，我们观察到相反的电子-空穴不对称性，和分别测量为0.86x 106 m/s和1.14 x106 m/s。 这种大的不对称性归因于石墨烯单层中的无质量狄拉克费米子在被吸引到带电缺陷时比被排斥时受到更强烈的散射。 显示英文摘要

摘要： The electron-hole symmetry in graphene monolayer, which is analogous to the inherent symmetric structure between electrons and positrons of the Universe, plays a crucial role in the chirality and chiral tunnelling of massless Dirac fermions. Here we demonstrate that both strain and charged-defect scattering could break this symmetry dramatically in graphene monolayer. In our experiment, the Fermi velocities of electrons and holes are measured directly through Landau level spectroscopy. In strained graphene with lattice deformation and curvature, the and are measured as 1.2 x 106 m/s and 1.02 x106 m/s, respectively. This giant asymmetry originates from enhanced next-nearest-neighbor hopping in the strained region. Around positively charged-defect, we observe opposite electron-hole asymmetry, and the and are measured to be 0.86x 106 m/s and 1.14 x106 m/s, respectively. Such a large asymmetry is attributed to the fact that the massless Dirac fermions in graphene monolayer are scattered more strongly when they are attracted to the charged-defect than when they are repelled from it.