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DOE OSTI · 2565889

Spontaneous Localization at a Potential Saddle Point from Edge State Reconstruction in a Quantum Hall Point Contact

Cohen, Liam A. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0000000272574105)·Samuelson, Noah L. [Univ. of California, Santa Barbara, CA (United States)]·Wang, Taige [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]·Klocke, Kai [University of California, Berkeley, CA (United States)] (ORCID:0000000295808509)·Reeves, Cian C. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0009000642581845)·Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)]·Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119)·Vijay, Sagar [Univ. of California, Santa Barbara, CA (United States)]·Zaletel, Michael P. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]·Young, Andrea F. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0000000159548028)
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Abstract

Quantum point contacts (QPCs) are an essential component in mesoscopic devices. Here, in this work, we study the transmission of quantum Hall edge modes through a gate-defined QPC in monolayer graphene. We observe resonant tunneling peaks and a nonlinear conductance pattern characteristic of Coulomb-blockaded localized states. The in-plane electric polarizability reveals the states are localized at a classically unstable electrostatic saddle point. We explain this unexpected finding within a self-consistent Thomas-Fermi model, finding that localization of a zero-dimensional state at the saddle point is favored whenever the applied confinement potential is sufficiently soft compared to the Coulomb energy. Our results provide a direct demonstration of Coulomb-driven reconstruction at the boundary of a quantum Hall system.

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71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICSfractional quantum Hall effectgraphenemesoscopicspoint contactsquantum Hall effect

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Cohen, Liam A. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0000000272574105), Samuelson, Noah L. [Univ. of California, Santa Barbara, CA (United States)], Wang, Taige [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Klocke, Kai [University of California, Berkeley, CA (United States)] (ORCID:0000000295808509), Reeves, Cian C. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0009000642581845), Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)], Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119), Vijay, Sagar [Univ. of California, Santa Barbara, CA (United States)], Zaletel, Michael P. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Young, Andrea F. [Univ. of California, Santa Barbara, CA (United States)] (ORCID:0000000159548028). 2025-02-19. Spontaneous Localization at a Potential Saddle Point from Edge State Reconstruction in a Quantum Hall Point Contact. https://doi.org/10.1103/physrevlett.134.076302

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