Fabrication and transfer of ultra-thin YBa$2$Cu$3$O$_{7-x}$ film on SrTiO$_3$ nanomembrane

D. Gr\"utzmacher; G. Potemkin; J.S. Madhira; M. Lyatti; T. Sch\"apers

arxiv: 2605.22303 · v1 · pith:ZP2W5VD3new · submitted 2026-05-21 · ❄️ cond-mat.supr-con

Fabrication and transfer of ultra-thin YBa2Cu3O_(7-x) film on SrTiO₃ nanomembrane

J.S. Madhira , G. Potemkin , D. Gr\"utzmacher , T. Sch\"apers , M. Lyatti This is my paper

Pith reviewed 2026-05-22 02:18 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con

keywords ultra-thin YBCO filmsnanomembrane transferhigh-Tc superconductorsvan der Waals interfacethermal boundary conductancesuperconducting microbridgesSiO2/Si substrates

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The pith

Ultra-thin YBCO films can be grown on STO nanomembranes, released by dissolving a sacrificial layer, and transferred to silicon substrates while keeping superconductivity intact.

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

The authors establish a fabrication process for millimeter-scale ultra-thin YBCO films on STO nanomembranes that allows the films to be released from their growth substrate and transferred onto silicon dioxide on silicon. They use high-pressure sputtering to grow the YBCO on a bilayer including a water-soluble sacrificial layer, then dissolve that layer to free the membrane. X-ray measurements confirm that the crystal quality survives the transfer, and electrical tests on patterned microbridges show a critical temperature of 88.8 K along with a critical current density of 6.8 MA per square centimeter at 77 K. The new van der Waals contact to the silicon substrate reduces thermal boundary conductance, which alters energy relaxation and makes transient resistive states more stable. This combination positions the transferred films as a route to high-temperature superconducting components that can be integrated with silicon photonic circuits.

Core claim

High-pressure sputtering produces high-quality ultra-thin YBCO films on STO/SCAO bilayers. Dissolution of the SCAO layer releases the STO nanomembrane carrying the YBCO film, which is then transferred to SiO2/Si substrates. Crystallinity is preserved as verified by X-ray diffraction. Patterned microbridges demonstrate superconductivity with Tc = 88.8 K and Jc = 6.8 MA/cm² at 77 K. The thermal boundary conductance at the van der Waals interface is much lower than in epitaxial films on bulk STO, resulting in changed energy relaxation dynamics and greater stability for transient resistive states.

What carries the argument

The STO nanomembrane carrying the YBCO film, released by dissolving the water-soluble SCAO sacrificial layer to form a van der Waals interface on SiO2/Si.

Load-bearing premise

Dissolving the water-soluble SCAO sacrificial layer releases the STO nanomembrane with the YBCO film intact without introducing defects or degrading the superconducting properties.

What would settle it

If patterned microbridges from the transferred films show a critical temperature below 80 K or a critical current density below 3 MA/cm² at 77 K, the claim of robust superconducting transport after transfer would be falsified.

Figures

Figures reproduced from arXiv: 2605.22303 by D. Gr\"utzmacher, G. Potemkin, J.S. Madhira, M. Lyatti, T. Sch\"apers.

**Figure 4.** Figure 4: FIG. 4. Superconducting properties of the Au/YBCO bridge on a SiO [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗

read the original abstract

The fabrication of free-standing ultra-thin films from high-temperature (high-Tc) superconductors is of great interest for the development of superconducting nanowire single-photon detectors with high operating temperatures. We successfully fabricate a millimeter-sized, high-quality, ultra-thin YBa$2$Cu$3$O$_{7-x}$ (YBCO) film on an SrTiO$_3$/Sr$_{1.5}$Ca$_{1.5}$Al$_2$O$_6$ (STO/SCAO) bilayer using high-pressure sputtering. The STO nanomembranes with the YBCO films are released by dissolving the water-soluble SCAO sacrificial layer and transferred onto the SiO2/Si substrate. X-ray diffraction confirms that STO and YBCO crystallinity is preserved following transfer onto SiO2/Si substrates. Microbridges patterned from the transferred YBCO films exhibit a critical temperature of 88.8 K and a critical current density of 6.8 MA/cm2 at 77 K, demonstrating robust superconducting transport after transfer. The thermal boundary conductance across the van der Waals interface between the STO nanomembrane with YBCO film and the SiO2/Si substrate, measured over 15-75 K, is significantly reduced compared to that of epitaxial YBCO film on bulk STO leading to modified energy relaxation and enhanced stability of transient resistive states. These results establish ultra-thin YBCO films on optically transparent STO nanomembranes as a platform for integrating high-Tc superconducting devices with SiO2/Si-based photonic structures.

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.

Desk Editor's Note private letter to a colleague

The transfer of ultra-thin YBCO via STO nanomembrane works with solid post-transfer Tc and Jc, but lacks before-and-after transport data to rule out degradation from the release step.

read the letter

The main takeaway is that the authors grew ultra-thin YBCO on a STO nanomembrane over a water-soluble SCAO sacrificial layer, released the membrane by dissolving the SCAO, and transferred it to SiO2/Si while keeping the film crystalline. After transfer they patterned microbridges that reached Tc of 88.8 K and Jc of 6.8 MA/cm2 at 77 K, and they measured a reduced thermal boundary conductance across the new interface compared with epitaxial YBCO on bulk STO. That combination of fabrication success and interface data is the concrete contribution here. The process steps are described clearly enough that someone could try to reproduce the growth and release sequence. The XRD check after transfer is a direct and appropriate way to confirm structural integrity survived the mechanical handling. Adding the thermal conductance measurement over 15-75 K is useful because it points to possible changes in energy relaxation that could affect device stability. The soft spot is the missing pre-transfer versus post-transfer transport comparison on the same film. The headline numbers are only shown after release and transfer, and they are benchmarked against general literature values rather than the starting film on the original substrate. Transport properties can shift from small changes in oxygen content or micro-strain that XRD would not catch, so the claim of fully robust transport rests on an assumption that the release step introduces no measurable damage. The abstract also omits quantitative details on thickness uniformity or error bars on the Jc and Tc values. This is a practical experimental fabrication paper aimed at groups trying to put high-Tc films onto silicon photonic platforms for detectors or circuits that can run at higher temperatures. A reader who needs a working recipe for transferred YBCO membranes would find the reported process and measured outcomes directly usable. It deserves peer review because the experimental claims are specific and falsifiable on their own terms; a referee could reasonably ask for the missing before-after data without rejecting the core result.

Referee Report

1 major / 2 minor

Summary. The paper reports successful fabrication of millimeter-scale ultra-thin YBCO films on STO/SCAO bilayers via high-pressure sputtering, followed by release through dissolution of the water-soluble SCAO sacrificial layer and transfer onto SiO2/Si substrates. XRD confirms preservation of STO and YBCO crystallinity post-transfer. Microbridges patterned on the transferred films exhibit Tc = 88.8 K and Jc = 6.8 MA/cm² at 77 K. Thermal boundary conductance across the van der Waals interface is measured between 15-75 K and found reduced relative to epitaxial YBCO on bulk STO, implying modified energy relaxation and enhanced stability of resistive states. The work positions these films as a platform for high-Tc superconducting devices integrated with Si-based photonics.

Significance. If the transfer process preserves superconducting properties without substantial degradation, this establishes a viable route to free-standing ultra-thin high-Tc films on optically transparent nanomembranes compatible with SiO2/Si platforms. The reduced thermal boundary conductance observation offers a concrete handle on interface engineering that could improve transient-state stability in devices such as SNSPDs. Credit is due for the direct experimental chain: sputtering growth, sacrificial-layer release, post-transfer XRD, transport measurements, and thermal-conductance data, all of which are falsifiable and reproducible in principle.

major comments (1)

[Transport characterization] Results section on transport properties: The headline claim of 'robust superconducting transport after transfer' rests on post-transfer Tc = 88.8 K and Jc = 6.8 MA/cm² values that are compared only to literature norms for epitaxial YBCO. No pre-transfer vs. post-transfer transport data on identical samples are presented, leaving the impact of SCAO dissolution, nanomembrane release, and transfer-induced strain or oxygen loss unquantified. Transport is more sensitive than XRD to such defects; a direct comparison would be required to substantiate the 'robust' assertion.

minor comments (2)

[Abstract] Abstract and experimental results: Quantitative metrics on film-thickness uniformity across the millimeter-scale area, defect density (e.g., from AFM or TEM), and experimental uncertainties or error bars on Tc, Jc, and thermal-conductance values are absent, hindering assessment of reproducibility.
[Fabrication methods] Methods: The high-pressure sputtering parameters (pressure, temperature, oxygen partial pressure) and the precise protocol for SCAO dissolution and membrane release should be stated with greater specificity to support replication.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the constructive and positive assessment of our manuscript. We address the single major comment below.

read point-by-point responses

Referee: Results section on transport properties: The headline claim of 'robust superconducting transport after transfer' rests on post-transfer Tc = 88.8 K and Jc = 6.8 MA/cm² values that are compared only to literature norms for epitaxial YBCO. No pre-transfer vs. post-transfer transport data on identical samples are presented, leaving the impact of SCAO dissolution, nanomembrane release, and transfer-induced strain or oxygen loss unquantified. Transport is more sensitive than XRD to such defects; a direct comparison would be required to substantiate the 'robust' assertion.

Authors: We agree that a direct pre- versus post-transfer comparison of transport properties on identical samples would provide the strongest possible evidence for minimal degradation. Such measurements are technically difficult in the present workflow: microbridge patterning and four-probe transport characterization are performed only after transfer onto SiO2/Si, while the as-grown film resides on the STO/SCAO bilayer. Attempting transport measurements prior to release risks damaging the fragile nanomembrane or altering the oxygen stoichiometry. We have therefore relied on (i) XRD data showing preservation of crystallinity and (ii) post-transfer Tc and Jc values that lie within the range reported for high-quality epitaxial YBCO films of comparable thickness. In the revised manuscript we will add an explicit discussion of these experimental constraints, qualify the wording around 'robust' transport, and include additional literature citations on transfer-induced effects in oxide films. revision: yes

Circularity Check

0 steps flagged

No circularity: purely experimental fabrication and characterization study

full rationale

The paper reports fabrication of YBCO films on STO nanomembranes, release by dissolving a sacrificial layer, transfer to SiO2/Si, and post-transfer measurements of Tc = 88.8 K and Jc = 6.8 MA/cm². All reported values are direct experimental measurements on fabricated devices with no derivations, model equations, fitted parameters presented as predictions, or self-referential claims. XRD and transport data are compared to external literature norms rather than to any internally generated prediction. No load-bearing steps reduce to self-definition, self-citation chains, or ansatz smuggling. The work is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on standard domain assumptions about layer compatibility and dissolution selectivity in oxide heterostructures; no free parameters or new entities are introduced.

axioms (1)

domain assumption The SCAO sacrificial layer can be selectively dissolved in water without damaging the overlying STO nanomembrane or YBCO film.
This premise is required for the release and transfer step described in the abstract.

pith-pipeline@v0.9.0 · 5843 in / 1321 out tokens · 57346 ms · 2026-05-22T02:18:58.337166+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Foundation/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

Microbridges patterned from the transferred YBCO films exhibit a critical temperature of 88.8 K and a critical current density of 6.8 MA/cm2 at 77 K

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

4 extracted references · 4 canonical work pages

[1]

H. J. Liu, J. Zhao, and T. H. Ly, Acs Nano 18, 11573 (2024)

work page 2024
[2]

S. H. Yun, T. E. le Cozannet, C. H. Christoffersen, E. Brand, T. S. Jespersen, and N. Pryds, Small 20 (2024)

work page 2024
[3]

J. Y. Moon et al., Adv Mater 38 (2026)

work page 2026
[4]

DGL film by Gel-Pak, https://www.gelpak.com/product-spotlight/dgl-film-for-crystal-vacuum- coating/. FIG. S9. Procedure of Au/YBCO/STO stack transfer using DGL film

work page

[1] [1]

H. J. Liu, J. Zhao, and T. H. Ly, Acs Nano 18, 11573 (2024)

work page 2024

[2] [2]

S. H. Yun, T. E. le Cozannet, C. H. Christoffersen, E. Brand, T. S. Jespersen, and N. Pryds, Small 20 (2024)

work page 2024

[3] [3]

J. Y. Moon et al., Adv Mater 38 (2026)

work page 2026

[4] [4]

DGL film by Gel-Pak, https://www.gelpak.com/product-spotlight/dgl-film-for-crystal-vacuum- coating/. FIG. S9. Procedure of Au/YBCO/STO stack transfer using DGL film

work page