Anomalous superconductivity in twisted MoTe<sub>2</sub> nanojunctions.

Jia, Yanyu; Song, Tiancheng; Zheng, Zhaoyi Joy; Cheng, Guangming; Uzan, Ayelet J; Yu, Guo; Tang, Yue; Pollak, Connor J et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Introducing superconductivity in topological materials can lead to innovative electronic phases and device functionalities. Here, we present a unique strategy for quantum engineering of superconducting junctions in moiré materials through direct, on-chip, and fully encapsulated 2D crystal growth. We achieve robust and designable superconductivity in Pd-metalized twisted bilayer molybdenum ditelluride (MoTe<sub>2</sub>) and observe anomalous superconducting effects in high-quality junctions across ~20 moiré cells. Unexpectedly, the junction develops enhanced, instead of weakened, superconducting behaviors, exhibiting fluctuations to a higher critical magnetic field compared to its adjacent Pd<sub>7</sub>MoTe<sub>2</sub> superconductor. In addition, the critical current further exhibits a notable V-shaped minimum at zero magnetic field. These features are unexpected in conventional Josephson junctions and absent in junctions of natural bilayer MoTe<sub>2</sub> created using the same approach. We discuss implications of these observations, including the possible formation of mixed even- and odd-parity superconductivity at the moiré junctions. Our results also demonstrate a pathway to engineer and investigate superconductivity in fractional Chern insulators.