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

Ke Ke Bai, Yi Cong Wei, Jia Bin Qiao, Si Yu Li, Long Jing Yin, Wei Yan, Jia Cai Nie, Lin He

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)

Abstract

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 tunneling of massless Dirac fermions. Here we demonstrate that both strain and charged-defect scattering could break this symmetry dramatically in a graphene monolayer. In our experiment, the Fermi velocities of electrons vFe and holes vFh are measured directly through Landau level spectroscopy. In strained graphene with lattice deformation and curvature, the vFe and vFh are measured as (1.21±0.03)×106m/s and (1.02±0.03)×106m/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 vFe and vFh are measured to be (0.86±0.02)×106m/s and (1.14±0.03)×106m/s, respectively. Such a large asymmetry is attributed to the fact that the massless Dirac fermions in a graphene monolayer are scattered more strongly when they are attracted to the charged defect than when they are repelled from it.

Original languageEnglish
Article number121405
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume92
Issue number12
DOIs
Publication statusPublished - 14 Sept 2015
Externally publishedYes

Fingerprint

Dive into the research topics of 'Detecting giant electron-hole asymmetry in a graphene monolayer generated by strain and charged-defect scattering via Landau level spectroscopy'. Together they form a unique fingerprint.

Cite this