Experimental evidence of plasmarons and effective fine structure constant in electron-doped graphene/h-BN heterostructure

Abstract Electron-electron interaction is fundamental in condensed matter physics and can lead to composite quasiparticles called plasmarons, which strongly renormalize the dispersion and carry information of electron-electron coupling strength as defined by the effective fine structure constant $${...

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Autores principales: Hongyun Zhang, Shuopei Wang, Eryin Wang, Xiaobo Lu, Qian Li, Changhua Bao, Ke Deng, Haoxiong Zhang, Wei Yao, Guorui Chen, Alexei V. Fedorov, Jonathan D. Denlinger, Kenji Watanabe, Takashi Taniguchi, Guangyu Zhang, Shuyun Zhou
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Lenguaje:EN
Publicado: Nature Portfolio 2021
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Acceso en línea:https://doaj.org/article/cebe098d57f84c03b2c3b710f956c57e
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Sumario:Abstract Electron-electron interaction is fundamental in condensed matter physics and can lead to composite quasiparticles called plasmarons, which strongly renormalize the dispersion and carry information of electron-electron coupling strength as defined by the effective fine structure constant $${\alpha }_{ee}^{* }$$ α e e * . Although h-BN with unique dielectric properties has been widely used as an important substrate for graphene, so far there is no experimental report of plasmarons in graphene/h-BN yet. Here, we report direct experimental observation of plasmaron dispersion in graphene/h-BN heterostructures through angle-resolved photoemission spectroscopy (ARPES) measurements upon in situ electron doping. Characteristic diamond-shaped dispersion is observed near the Dirac cone in both 0° (aligned) and 13.5° (twisted) graphene/h-BN, and the electron-electron interaction strength $${\alpha }_{ee}^{* }$$ α e e * is extracted to be $${\alpha }_{ee}^{* }\approx 0.9\pm 0.1$$ α e e * ≈ 0.9 ± 0.1 , highlighting the important role of electron-electron interaction. Our results suggest graphene/h-BN as an ideal platform for investigating strong electron-electron interaction with weak dielectric screening, and lays fundamental physics for gate-tunable nano-electronics and nano-plasmonics.