Vortex Dynamics in Magic-Angle Twisted Graphene

Marta Perego; Peter Koopmann; Clara Galante Agero; Alexandra Mestre Torà; Takashi Taniguchi; Kenji Watanabe; Vadim Geshkenbein; Gianni Blatter; Thomas Ihn; Klaus Ensslin

Vortex Dynamics in Magic-Angle Twisted Graphene

超导电性 2026-07-09 v1 介观与纳米尺度物理

作者: Marta Perego , Peter Koopmann , Clara Galante Agero , Alexandra Mestre Torà , Takashi Taniguchi , Kenji Watanabe , Vadim Geshkenbein , Gianni Blatter , Thomas Ihn , Klaus Ensslin

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摘要

We use a gate-defined Josephson junction (JJ) device made from twisted-layer graphene for studying vortex dynamics in two dimensions. The JJ sensor signals the presence of individual vortices in the superconducting leads nearby the junction through shifts in the Fraunhofer interference pattern of the magnetic-field-dependent critical current $I_c(B)$ across the junction. Rapid vortex fluctuations manifest as telegraph-type noise in time traces of the junction voltage $V(t)$ . Measurements of $I_c(B)$ and $V(t)$ are interpreted in terms of multi-vortex processes where fast vortex fluctuations in the leads are modulated by quasi-stationary vortices trapped in the leads. The different timescales associated with these processes allow for their disentangling and quantitative analysis. Tracking the temperature dependence of the vortex-dynamical rates between $T = 7$ mK and $T = 120$ mK, we find that the creep type vortex motion is thermally activated above $T \approx 100$ mK, while the saturation of rates below $T \approx 80$ mK is suggestive of a sharp transition to macroscopic quantum tunneling of vortices.

引用

@article{arxiv.2607.08585,
  title  = {Vortex Dynamics in Magic-Angle Twisted Graphene},
  author = {Marta Perego and Peter Koopmann and Clara Galante Agero and Alexandra Mestre Torà and Takashi Taniguchi and Kenji Watanabe and Vadim Geshkenbein and Gianni Blatter and Thomas Ihn and Klaus Ensslin},
  journal= {arXiv preprint arXiv:2607.08585},
  year   = {2026}
}