グラフェンで非従来型超伝導を観測、室温超伝導の手がかりに(Physicists observe evidence of unconventional superconductivity in graphene)

2025-11-06 マサチューセッツ工科大学(MIT)

MIT物理学科の研究チームは、三層のグラフェンを特定角度でねじって積層した「マジックアングル三層グラフェン(MATTG)」において、非従来型超伝導の直接的証拠を観測した。独自開発の電子トンネル測定装置により、超伝導状態のエネルギーギャップをリアルタイムで可視化し、その形状が通常の超伝導体と異なることを確認。これにより、MATTGでは異なる電子相互作用機構が働くと示された。成果は室温超伝導設計の手掛かりとなる。研究はScience誌に掲載。

グラフェンで非従来型超伝導を観測、室温超伝導の手がかりに(Physicists observe evidence of unconventional superconductivity in graphene)
MIT researchers observed clear signatures of unconventional superconductivity in magic-angle twisted trilayer graphene (MATTG). The image illustrates pairs of superconducting electrons (yellow spheres) traveling through MATTG, as the team’s new method (represented by magnifying glass) probes the material’s unconventional superconducting gap (represented by the V-shaped beam).Image: Sampson Wilcox and Emily Theobald, MIT RLE

<関連情報>

モアレグラフェンにおけるノード超伝導ギャップの実験的証拠 Experimental evidence for nodal superconducting gap in moiré graphene

Jeong Min Park, Shuwen Sun, Kenji Watanabe, Takashi Taniguchi, and Pablo Jarillo-Herrero
Science  Published:6 Nov 2025
DOI:https://doi.org/10.1126/science.adv8376

Abstract

Understanding the nature of superconductivity in magic-angle graphene remains challenging. A key difficulty lies in discerning the different energy scales in this strongly interacting system, particularly the superconducting gap. Here, we report simultaneous tunneling spectroscopy and transport measurements of magic-angle twisted trilayer graphene. This approach allows us to identify two coexisting V-shaped tunneling gaps with different energy scales: a distinct low-energy superconducting gap that vanishes at the superconducting critical temperature and magnetic field, and a higher-energy pseudogap. The superconducting tunneling spectra display a linear gap-filling behavior with temperature and magnetic field and exhibit the Volovik effect, consistent with a nodal order parameter. Our work suggests an unconventional nature of the superconducting gap and establishes an experimental framework for multidimensional investigation of tunable quantum materials.

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