Gate-Tunable Ambipolar Josephson Current in a Topological Insulator

作者：Bomin Zhang, Xiaoda Liu, Junjie Qi, Ling‐Jie Zhou, Deyi Zhuo, Han Tay, Hongtao Rong, Annie G. Wang, Zhiyuan Xi, Chao Liu, Chui‐Zhen Chen, Cui‐Zu Chang · 发表于：Nano Letters · 年份：2025 · DOI：10.1021/acs.nanolett.5c04854 · 被引用次数：1 · 研究领域：Topological Materials and Phenomena、Chemical and Physical Properties of Materials、Graphene research and applications

Dirac surface states in a topological insulator (TI) with proximity-induced superconductivity offer a promising platform for realizing Majorana physics. In this work, we demonstrate gate-tunable ambipolar Josephson current in lateral Josephson junction (JJ) devices based on bulk-insulating (Bi,Sb) 2 Te 3 thin films grown by molecular beam epitaxy (MBE). For thinner films, the supercurrent exhibits pronounced gate-tunable ambipolar behavior and is significantly suppressed as the chemical potential approaches the Dirac point yet persists across it. In contrast, thicker films exhibit a much weaker ambipolar response. Moreover, we find that the supercurrent becomes significantly less resilient to external magnetic fields when the chemical potential is tuned near the Dirac point. By performing numerical simulations, we attribute the asymmetric supercurrent observed in thicker TI films to the coexistence of Dirac surface states and bulk conduction channels. The demonstration of gate-tunable ambipolar Josephson transport establishes a foundation for the future exploration of electrically tunable Majorana modes.