Coexistence of electron whispering-gallery modes and atomic collapse states in graphene/WSe2 heterostructure quantum dots

• Published in: Nature communications Vol. 13; no. 1; p. 1597
• Main Authors: Zheng, Qi, Zhuang, Yu-Chen, Sun, Qing-Feng, He, Lin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.03.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 147/138; 639/301/357/1017; 639/925/918/1052; Coexistence; Collapse; Current carriers; Electrons; Fermions; Graphene; Heavy nuclei; Heterostructures; Humanities and Social Sciences; Light speed; Magnetic fields; multidisciplinary; Quantum dots; Relativistic effects; Science; Science (multidisciplinary); Velocity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-29251-2

The relativistic massless charge carriers with a Fermi velocity of about c /300 in graphene enable us to realize two distinct types of resonances (here, c is the speed of light in vacuum). One is the electron whispering-gallery mode in graphene quantum dots arising from the Klein tunneling of the massless Dirac fermions. The other is the atomic collapse state, which has never been observed in experiment with real atoms due to the difficulty of producing heavy nuclei with charge Z > 170; however, they can be realized near a Coulomb impurity in graphene with a charge Z ≥ 1 because of the “small” velocity of the Dirac excitations. Here we demonstrate that both the electron whispering-gallery modes and atomic collapse states coexist in graphene/WSe 2 heterostructure quantum dots due to the Coulomb-like potential near their edges. By applying a perpendicular magnetic field, we explore the evolution from the atomic collapse states to unusual Landau levels in the collapse regime. The whispering-gallery mode and the atomic collapse state are two distinct resonances in condensed matter associated with relativistic massless charge carriers. Now, it is shown that these states can coexist in graphene/WSe 2 heterostructure quantum dots.