[PL1] Plenary 1

8:30 AM - 9:15 AM JST(11:30 PM - 12:15 AM UTC)

[PL1] Scanning SQUID-on-tip magnetic and thermal imaging: nanoscale probe of superconductivity and strongly correlated electronic systems

*Eli Zeldov¹ (1. Weizmann Institute of Science (Israel))

Keywords:

SQUID,Vortex dynamics,Graphene,Magnetic imaging

Over the past decade we have developed a family of scanning probes based on a superconducting quantum interference device fabricated directly on the apex of a pulled quartz pipette—SQUID-on-tip (SOT). The self-aligned process yields SOT diameters down to 40 nm, extremely low flux noise of 50 nΦ₀/Hz^1/2, and record spin sensitivity of better than 1 μ_B/Hz^1/2 [1]. The SOT geometry allows scanning at tip–sample spacing of few tens of nanometers, operation in elevated magnetic fields, and over a span of temperatures down to mK range. These capabilities enable quantitative, non-invasive mapping of magnetic textures, current distributions, dynamic responses, as well as scanning-gate microscopy.Using SOT magnetometry of vortex matter, we resolved the pinning potential and nm-scale trajectories of individual vortices with displacement sensitivity down to ~10 pm, directly imaging elementary depinning processes [2]. When the critical current is exceeded, we visualized super-fast vortex flow with velocities up to tens of km/s, uncovering channel flow with branching instabilities and dynamic transitions as the resistive state emerges [3]. Recently, we have extended vortex imaging beyond superconductors, providing the first direct observation of vortices in an electron fluid and hydrodynamic to laminar-flow transition in van der Waals materials [4].The SOT microscopy provides a novel tool to study spontaneous time-reversal-symmetry-breaking that occurs in topological and strongly interacting electron systems including graphene and transition metal dichalcogenides. Our studies have revealed Berry-curvature-induced orbital magnetization in rhombohedral graphene [5] and Chern mosaic in magic-angle twisted bilayer graphene (MATBG) [6]. Moreover, it has provided the first measurement of thermodynamic quantum oscillations in magnetization in graphene systems, including trilayer [7], bilayer moiré [8], twisted trilayer [9], and MATBG structures [10], allowing very accurate reconstruction of the band structure, disorder, and interaction effects with nanoscale spatial resolution. Finally, we transformed the SOT into an ultra-sensitive scanning nano-thermometer, enabling the first thermal imaging at cryogenic temperatures with µK sensitivity and nanoscale resolution [11]. This platform visualized heat released by electron scattering off single atomic defect in graphene, separated “work” from “dissipation” at quantum Hall edges via simultaneous thermal and scanning-gate imaging [12], uncovered long-range non-topological edge currents in graphene [13], allowed cryogenic study of thermoelectric effects [14], and provided a new method for electron thermometry [15]. [1] D. Vasyukov et al., Nature Nanotech. 8, 639 (2013).[2] L. Embon et al., Scientific Reports 5, 7598, (2015).[3] L. Embon et al., Nature Commun. 8, 85 (2017).[4] A. Aharon-Steinberg et al., Nature 607, 74 (2022).[5] N. Auerbach et al., arXiv:2506.21523; M. Uzan et al., arXiv:2507.20647.[6] S. Grover et al., Nature Phys. 18, 885 (2022).[7] H. Zhou et al., Nature 624, 275 (2023) [8] M. Bocarsly et al., Science 383, 42 (2024).[9] M. Bocarsly et al., Nature Phys. 21, 421 (2025).[10] A. Uri et al., Nature 581, 47 (2020).[11] D. Halbertal et al., Nature 539, 407 (2016).[12] D. Halbertal et al., Science 358, 1303 (2017). [13] A. Aharon-Steinberg et al., Nature 593, 528 (2021).[14] T. Völkl et al., Nature Phys. 20, 976 (2024).[15] S. Kumar et al., arXiv:2507.20647.

Presentation Materials
https://iss-archives.jp/iss2025.jp/slides/PL1.pdf
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