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arxiv: 2601.13298 · v2 · submitted 2026-01-19 · ❄️ cond-mat.supr-con

Towards reliable electrical measurements of superconducting devices inside a transmission electron microscope

Joachim Dahl Thomsen , Michael I. Faley , Joseph Vimal Vas , Alexander Clausen , Thibaud Denneulin , Dominik Biscette , Denys Sutter , Peng-Han Lu
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Rafal E. Dunin-Borkowski
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Pith reviewed 2026-05-16 13:17 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con
keywords NbN superconducting devicestransmission electron microscopylow-temperature electrical transportthermal radiation shieldcryogenic sample holderoperando TEM measurementsquantum device characterization
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The pith

Electrical transport on NbN superconducting devices reaches an estimated 8-9 K inside a TEM via an optimized thermal radiation shield.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows that a continuous-flow liquid-helium sample holder can be modified with an improved thermal radiation shield to reach base temperatures low enough for superconductivity in NbN devices during TEM operation. This setup allows simultaneous electrical measurements and high-resolution imaging inside the microscope. A sympathetic reader would care because it creates a route to obtain structural, spectroscopic, and transport data from the exact same nanoscale device at cryogenic conditions. The work also records that the electron beam and objective lens excitation each disturb the superconducting transition, so measurements must account for those effects. Supporting calculations illustrate why shielding against radiation from the lens pole pieces is essential to keep the sample cold.

Core claim

By optimizing the thermal radiation shield to limit radiation from the objective lens pole pieces, the continuous-flow liquid-helium-cooled holder achieves an estimated base sample temperature of 8-9 K, as read out from the superconducting transition temperatures of the NbN devices. Both electron beam illumination and objective lens excitation are found to perturb the superconducting state. The holder’s imaging stability at low temperature is confirmed by resolving magnetic domain structures in CrBr3, and calculations confirm the role of cryo-shielding in reducing thermal load on the device.

What carries the argument

The optimized thermal radiation shield that blocks radiation from the nearby pole pieces of the objective lens in the continuous-flow liquid-helium sample holder.

Load-bearing premise

The superconducting transition temperature of the NbN devices accurately reflects the true sample temperature with only minimal perturbation from electron beam illumination or objective lens excitation.

What would settle it

Placing a calibrated temperature sensor directly on the device or stage and recording whether its reading matches the transition temperature extracted from the NbN devices under the same beam and lens conditions.

Figures

Figures reproduced from arXiv: 2601.13298 by Alexander Clausen, Denys Sutter, Dominik Biscette, Joachim Dahl Thomsen, Joseph Vimal Vas, Michael I. Faley, Peng-Han Lu, Rafal E. Dunin-Borkowski, Thibaud Denneulin.

Figure 1
Figure 1. Figure 1: Measurement setup overview. (a) Photograph of the helium dewar, helium transfer line inserted into the back of the TEM holder, and the arm of the damping stage that supports the helium transfer line. (b) Photograph of the temperature sensor readout, lock-in amplifier, and grounding box. A diagram of the electrical measurement setup is given in Fig. S2. In (a, b) the background hasbeen blacked out to emphas… view at source ↗
Figure 2
Figure 2. Figure 2: Resistance measurements of superconducting NbN devices. (a) Resistance plotted against thermometer temperature for device 1. The measurements were performed in the TEM in LTEM mode without electron beam illumination. The black and green data were obtained using the modified and regular cryo-shield, and using test currents of 500 and 100 nA, respectively. The red data were obtained from a separate PPMS meas… view at source ↗
Figure 3
Figure 3. Figure 3: Effect of TEM imaging. (a) Resistance plotted against time during an experiment where the beam is initially blanked for 15 s, and then the beam current is decreased every 15 s by increasing the spot size. The device becomes superconducting between each spot size change because the electron beam is briefly blanked during the change. The electron beam current density is indicated on the figure. The experimen… view at source ↗
Figure 4
Figure 4. Figure 4: Effect of magnetic field. (a) Resistance plotted against time during an experiment where the electron beam is blanked, and the magnetic field is increased in steps of 100 mT every 10 s as indicated on the plot. The thermometer temperature was 5.9 K during the measurement. (b) Average resistance plotted against magnetic field for two different experiments performed at thermometer readings of T=5.9 and 6.4 K… view at source ↗
Figure 5
Figure 5. Figure 5: Thermal radiation heat loads. The red and blue curves show the net radiative power (direct line-of-sight) on the device, Pdir, calculated using Eq. 4, for Tsh = 30 K (blue) and 50 K (red). The radiative power transmitted through the imaging apertures, Pin, is plotted in black. The inset shows a diagram of the model. The horizontal dotted line indicates the direct line-of-sight contribution without a cryo-s… view at source ↗
read the original abstract

Correlating structure with electronic functionality is central to the engineering of quantum materials and devices whose properties depend sensitively on disorder. Transmission electron microscopy (TEM) offers high spatial resolution together with access to structural, electronic, and magnetic degrees of freedom. However, operando electrical transport measurements on functional quantum devices remain rare, particularly at liquid helium temperature. Here, we demonstrate electrical transport measurements of niobium nitride (NbN) devices inside a TEM using a continuous-flow liquid-helium-cooled sample holder. By optimizing a thermal radiation shield to limit radiation from the nearby pole pieces of the objective lens, we achieve an estimated base sample temperature of 8-9 K, as inferred from the superconducting transition temperatures of our devices. We find that both electron beam illumination and objective lens excitation perturb the superconducting state. In addition, we evaluate the imaging capabilities and stability of the sample holder at low temperature by imaging the magnetic domain structure of the van der Waals ferromagnet CrBr$_3$. Finally, we perform calculations that underscore the importance of cryo-shielding for minimizing thermal radiation onto the device. This capability enables correlative low-temperature TEM studies, in which structural, spectroscopic, and electrical transport data can be obtained from the same device, thereby providing a platform for probing the microscopic origins of quantum phenomena.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 1 minor

Summary. The manuscript demonstrates electrical transport measurements on NbN superconducting devices inside a TEM using a continuous-flow liquid-helium holder. By optimizing a thermal radiation shield to reduce radiation from the objective lens pole pieces, the authors infer a base sample temperature of 8-9 K from the devices' superconducting transition temperatures. They report that both electron beam illumination and objective lens excitation perturb the superconducting state, evaluate imaging stability via magnetic domains in CrBr3, and present calculations highlighting the role of cryo-shielding.

Significance. If the 8-9 K base temperature is reliably established with quantified perturbations, the work provides a platform for correlative low-temperature TEM studies combining structural, spectroscopic, and transport data on the same quantum device. This addresses a clear gap in operando cryo-TEM for superconducting and quantum materials.

major comments (1)
  1. [Abstract and temperature inference section] Abstract and temperature measurement section: The central claim of an 8-9 K base temperature is inferred solely from NbN Tc values, yet the text states that beam illumination and lens excitation both perturb the superconducting state without providing quantitative Tc shift data, error bars on the inferred temperature, or confirmation that base Tc scans were performed with beam blanked and lens off. This is load-bearing for all subsequent claims about cryo-TEM capability.
minor comments (1)
  1. [Abstract] The abstract mentions 'calculations that underscore the importance of cryo-shielding' but does not specify which section or figure presents the quantitative radiation heat load results.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their constructive assessment and for identifying the need for stronger quantification of our temperature measurements. We have revised the manuscript to address this central concern by adding the requested quantitative data and clarifications, while preserving the overall scope and claims of the work.

read point-by-point responses

  1. Referee: [Abstract and temperature inference section] Abstract and temperature measurement section: The central claim of an 8-9 K base temperature is inferred solely from NbN Tc values, yet the text states that beam illumination and lens excitation both perturb the superconducting state without providing quantitative Tc shift data, error bars on the inferred temperature, or confirmation that base Tc scans were performed with beam blanked and lens off. This is load-bearing for all subsequent claims about cryo-TEM capability.

    Authors: We agree that the temperature inference is load-bearing and that the original manuscript presented the perturbations only qualitatively. In the revised version we have added a new supplementary figure showing full superconducting transition curves measured on multiple NbN devices under four conditions (beam blanked/lens off; beam on/lens off; beam blanked/lens on; beam on/lens on). Error bars are now reported from device-to-device variation and from repeated thermal cycles. The text has been updated to state explicitly that the base-temperature Tc values used for the 8–9 K inference were acquired with the electron beam blanked and the objective lens current set to zero. These additions directly quantify the perturbations (approximately 1–2 K shifts) and confirm the conditions under which the base temperature was established. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The manuscript is an experimental report on cryo-TEM electrical measurements. The base-temperature claim (8-9 K) is obtained by direct inference from the observed superconducting transition of NbN devices using standard, externally calibrated Tc values for that material; no parameter is fitted to the target result and then re-labeled as a prediction. No equations, uniqueness theorems, or ansatzes are introduced via self-citation, and the radiation-shield calculations are independent first-principles estimates that do not loop back to the measured Tc. The derivation chain therefore remains self-contained against external benchmarks and does not reduce to its own inputs by construction.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard assumptions about superconductivity as a thermometer and the effectiveness of passive shielding; no new entities or heavily fitted parameters are introduced.

free parameters (1)
  • shield geometry parameters
    Design choices for the thermal radiation shield optimized to minimize heat load from pole pieces.
axioms (1)
  • domain assumption Superconducting transition temperature of NbN accurately reflects local sample temperature
    Invoked to estimate 8-9 K base temperature from measured Tc.

pith-pipeline@v0.9.0 · 5568 in / 1087 out tokens · 28282 ms · 2026-05-16T13:17:30.454818+00:00 · methodology

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