Signature of gate tunable superconducting network in twisted bilayer graphene

Yingbo Wang; Yingzhuo Han; Lu Cao; Xun-Jiang Luo; Yucheng Xue; Jiefei Shi; Xiaomeng Wang; Xiangjia Bai; Junnan Jiang; Ziyi Tian; Kenji Watanabe; Takashi Taniguchi; Fengcheng Wu; Qing-feng Sun; Hong-Jun Gao; Yuhang Jiang; Jinhai Mao

arXiv · 2507.04287

Signature of gate tunable superconducting network in twisted bilayer graphene

Yingbo Wang·Yingzhuo Han·Lu Cao·Xun-Jiang Luo·Yucheng Xue·Jiefei Shi·Xiaomeng Wang·Xiangjia Bai·Junnan Jiang·Ziyi Tian·Kenji Watanabe·Takashi Taniguchi·Fengcheng Wu·Qing-feng Sun·Hong-Jun Gao·Yuhang Jiang·Jinhai Mao

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Abstract

Twisted van der Waals materials provide a tunable platform for investigating two-dimensional superconductivity and quantum phases. Using spectra-imaging scanning tunneling microscopy, we study the superconducting states in twisted bilayer graphene and track their evolution from insulating phases. Gate-dependent spectroscopic measurements reveal two distinct regimes: under-doped ({\nu} = -2.3) and optimally doped ({\nu} = -2.6). In the under-doped regime, partial superconductivity arises, forming a network interspersed with non-gapped regions. At optimal doping, the entire unit cell demonstrates superconductivity, with gap size modulation showing an anti-correlation with the local density of states. This gate-dependent transition from an insulating phase to a modulated superconductor uncovers an unexpected spatial hierarchy in pairing behavior and offers direct microscopic insights to constrain theories of superconductivity in moir\'e systems.

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Yingbo Wang, Yingzhuo Han, Lu Cao, Xun-Jiang Luo, Yucheng Xue, Jiefei Shi, Xiaomeng Wang, Xiangjia Bai, Junnan Jiang, Ziyi Tian, Kenji Watanabe, Takashi Taniguchi, Fengcheng Wu, Qing-feng Sun, Hong-Jun Gao, Yuhang Jiang, Jinhai Mao. 2025-07-06. Signature of gate tunable superconducting network in twisted bilayer graphene. https://arxiv.org/abs/2507.04287

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