pith. sign in

arxiv: 2604.11047 · v1 · submitted 2026-04-13 · ❄️ cond-mat.supr-con

Type-II superconductivity in the Dirac semimetal PdTe2

Ritu Gupta , Catherine Witteveen , Debarchan Das , Fabian O. von Rohr , Rustem Khasanov This is my paper

Pith reviewed 2026-05-10 16:10 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con
keywords PdTe2Dirac semimetaltype-II superconductivityflux line latticemuon spin relaxations-wave gapvan der Waals materialdisorder tuning
0
0 comments X

The pith

Mosaic crystals of the Dirac semimetal PdTe2 display type-II superconductivity with a flux-line lattice induced by disorder, showing a fully gapped s-wave order parameter.

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

The study examines superconducting properties in mosaic PdTe2 crystals through muon spin relaxation, ac susceptibility, and resistivity measurements. Two transitions appear near 1.8 K and 1.6 K, and transverse-field μSR spectra show a diamagnetic shift plus Gaussian broadening below these temperatures, signaling the presence of a bulk flux-line lattice. This establishes type-II behavior, attributed to disorder in the mosaic samples, in contrast to earlier type-I classifications. The magnetic penetration depth follows an s-wave gap form without nodes. The authors conclude that PdTe2 provides a platform to explore the combined effects of non-trivial band topology, surface superconductivity, and bulk type-II superconductivity within a van-der-Waals layered compound, with disorder offering a route to switch between the two superconducting types.

Core claim

In mosaic crystals of PdTe2, zero-field and transverse-field μSR together with susceptibility data reveal two superconducting transitions and, below them, a clear diamagnetic shift accompanied by Gaussian broadening of the Fourier-transformed spectra. These features demonstrate the formation of a flux-line lattice characteristic of type-II superconductivity. The temperature dependence of the penetration depth is well described by an isotropic s-wave gap, indicating a fully gapped order parameter. The type-II character is linked to mosaic disorder, which the measurements suggest can convert the superconductivity from the type-I state reported in earlier work.

What carries the argument

Transverse-field muon spin rotation detecting the inhomogeneous internal field distribution produced by a disordered flux-line lattice in the superconducting state.

If this is right

  • Disorder provides a practical control parameter to switch PdTe2 superconductivity between type-I and type-II regimes.
  • The material combines bulk type-II superconductivity with potential surface superconductivity and Dirac topology inside a single van-der-Waals structure.
  • The s-wave gap implies conventional pairing that coexists with the semimetal band structure.
  • Similar disorder tuning may apply to other layered Dirac or topological semimetals.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Controlled defect engineering could be used to stabilize desired superconducting states in related van-der-Waals topological materials.
  • Direct comparison of mosaic versus single-crystal samples would isolate the role of surface versus bulk contributions.
  • The two observed transition temperatures may reflect distinct regions or phases whose relative weight depends on sample quality.

Load-bearing premise

The observed diamagnetic shift and Gaussian broadening arise from a bulk type-II flux-line lattice caused by mosaic disorder rather than from surface superconductivity, domain-wall effects, or experimental artifacts.

What would settle it

High-quality single crystals of PdTe2 without mosaic disorder that show complete Meissner expulsion and no flux-line lattice signatures in μSR spectra would falsify the disorder-induced type-II claim.

Figures

Figures reproduced from arXiv: 2604.11047 by Catherine Witteveen, Debarchan Das, Fabian O. von Rohr, Ritu Gupta, Rustem Khasanov.

Figure 1
Figure 1. Figure 1: FIG. 1: (a) Powder X-ray pattern of crushed mosaic crystals measured in transmission mode with Cu K [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2: (a) Asymmetry-time [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3: (a) Temperature dependent inverse squared magnetic penetration depth [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
read the original abstract

We report on the microscopic superconducting properties of the Dirac semimetal PdTe2. In this study, we have focused on mosaic crystals of PdTe2, and used detailed zero field and transverse field muon spin relaxation/rotation ($\mu$SR), ac-magnetic susceptibility, and resistivity measurements to investigate their superconducting properties. The magnetic susceptibility measurements reveal two superconducting transition temperatures at 1.8 and 1.6~K, respectively, in agreement with earlier reports. In contrary to these reports, we find that these mosaic PdTe2 crystals, are not type-I, but rather type-II superconductors. In fact, we observe the clear manifestation of a flux line lattice through a clear diamagnetic shift and Gaussian broadening of the Fourier spectra in the superconducting state. This behavior is likely caused by the disorder in the mosaic crystals of PdTe2 studied here. Our analysis of the superconducting order parameter by the means of temperature dependent magnetic penetration depth $\lambda(T)$ reveals a fully gapped superconducting state that can be well-fitted using an s-wave symmetric gap. We find that PdTe2 is a promising model system for the investigation and interplay of non-trivial topology, surface superconductivity, and type-II bulk superconductivity in a van-der-Waals material. Moreover, our results indicate that the superconductivity in this material can be easily modified from type-I to type-II by disorder in the system.

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

2 major / 2 minor

Summary. The manuscript reports μSR, ac-magnetic susceptibility, and resistivity measurements on mosaic crystals of the Dirac semimetal PdTe2. It claims these crystals are type-II superconductors (contrary to prior type-I reports) due to mosaic disorder, with evidence from a diamagnetic shift and Gaussian broadening in the μSR Fourier spectra below Tc interpreted as a disordered flux-line lattice. Temperature-dependent penetration depth λ(T) is analyzed and fitted to an s-wave gap, indicating a fully gapped state. PdTe2 is positioned as a model system for studying the interplay of topology, surface superconductivity, and bulk type-II superconductivity in a van der Waals material, with superconductivity tunable from type-I to type-II by disorder.

Significance. If the central claim is substantiated, this would establish mosaic PdTe2 as a tunable platform for exploring non-trivial topology with bulk type-II superconductivity and surface effects in a van der Waals Dirac semimetal. The multi-technique approach (μSR for microscopic vortex lattice signatures combined with susceptibility and resistivity) is a strength, providing direct observables rather than parameter-dependent derivations.

major comments (2)
  1. [Abstract and μSR results] Abstract and μSR data presentation: The central claim of bulk type-II behavior rests on the diamagnetic shift and Gaussian broadening in the Fourier spectra being due to a disordered flux-line lattice from mosaic disorder. However, no quantitative vortex-lattice field distribution modeling, reported penetration depth values, error bars on the relaxation rates, or explicit checks separating bulk volume fraction from surface superconductivity (known to exist in PdTe2) or domain-wall artifacts are provided. This leaves open whether the signal is bulk-dominated or surface/experimental in origin.
  2. [Discussion] Type-I to type-II transition claim: The assertion that disorder easily modifies the superconductivity from type-I to type-II lacks comparison of the observed μSR relaxation to expected Hc1/Hc2 scales or simulations that would rule out alternative explanations such as experimental misalignment in mosaic crystals. Without these, the disorder-induced transition remains interpretive rather than quantitatively demonstrated.
minor comments (2)
  1. [Results] The two transition temperatures (1.8 K and 1.6 K) from susceptibility are mentioned but their assignment to bulk versus surface or which is used for the λ(T) analysis should be clarified with reference to specific figures.
  2. [Analysis] Notation for the penetration depth λ(T) and gap amplitude should be consistent between text, equations, and figures.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their thorough review and valuable comments on our manuscript. We address each of the major comments below and have made revisions to the manuscript to clarify and strengthen our claims where possible.

read point-by-point responses

  1. Referee: Abstract and μSR data presentation: The central claim of bulk type-II behavior rests on the diamagnetic shift and Gaussian broadening in the Fourier spectra being due to a disordered flux-line lattice from mosaic disorder. However, no quantitative vortex-lattice field distribution modeling, reported penetration depth values, error bars on the relaxation rates, or explicit checks separating bulk volume fraction from surface superconductivity (known to exist in PdTe2) or domain-wall artifacts are provided. This leaves open whether the signal is bulk-dominated or surface/experimental in origin.

    Authors: We thank the referee for this important comment. While the original manuscript focused on presenting the key observations of diamagnetic shift and Gaussian broadening as signatures of a flux-line lattice, we acknowledge the need for more quantitative support. In the revised manuscript, we have added a section with quantitative vortex-lattice field distribution modeling based on the London approximation for a disordered lattice. We now report the penetration depth values extracted from the data, including error bars on the relaxation rates in the figures and text. Additionally, we have included an analysis of the μSR asymmetry to confirm that the signal originates from the bulk volume fraction, with discussions addressing potential surface superconductivity and domain-wall effects, showing they do not dominate the observed signal. revision: yes

  2. Referee: Type-I to type-II transition claim: The assertion that disorder easily modifies the superconductivity from type-I to type-II lacks comparison of the observed μSR relaxation to expected Hc1/Hc2 scales or simulations that would rule out alternative explanations such as experimental misalignment in mosaic crystals. Without these, the disorder-induced transition remains interpretive rather than quantitatively demonstrated.

    Authors: We agree that the transition claim benefits from quantitative backing. We have revised the discussion section to include comparisons of the μSR relaxation rates to the expected Hc1 and Hc2 values for PdTe2, drawing from prior reports on the clean limit. We also provide arguments and preliminary simulations showing that the observed field distribution is inconsistent with simple misalignment but rather matches expectations for a disordered vortex lattice in mosaic crystals. This makes the disorder-induced type-I to type-II transition more quantitatively supported. revision: yes

Circularity Check

0 steps flagged

No circularity: claims rest on direct experimental observables without self-referential reduction.

full rationale

The paper's central claims derive from raw μSR spectra (diamagnetic shift and Gaussian broadening below Tc), ac-susceptibility transitions at 1.8 K and 1.6 K, and resistivity data. These are interpreted as evidence for bulk type-II behavior induced by mosaic disorder, with λ(T) subsequently fitted to an s-wave gap function. No equation or step reduces by construction to its own inputs (e.g., no fitted parameter is renamed as a prediction, no ansatz is smuggled via self-citation, and no uniqueness theorem is invoked). The fitting of λ(T) is a conventional model comparison to measured penetration-depth values and does not force the type-I/II classification. The derivation chain is therefore self-contained and externally falsifiable against prior type-I reports.

Axiom & Free-Parameter Ledger

1 free parameters · 0 axioms · 0 invented entities

The interpretation that the μSR line broadening signals a bulk flux-line lattice rests on the assumption that mosaic disorder is the dominant source of pinning and that surface or domain effects do not dominate the signal.

free parameters (1)
  • superconducting gap amplitude
    Fitted parameter in the temperature-dependent penetration-depth analysis; value not stated in abstract.

pith-pipeline@v0.9.0 · 5563 in / 1149 out tokens · 76925 ms · 2026-05-10T16:10:32.551016+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

37 extracted references · 37 canonical work pages

  1. [1]

    Yang , author S

    author H. Yang , author S. W. Kim , author M. Chhowalla , and author Y. H. Lee , journal Nature Physics volume 13 , pages 931 ( year 2017 )

    work page 2017

  2. [2]

    author C. W. Nicholson , author M. Rumo , author A. Pulkkinen , author G. Kremer , author B. Salzmann , author M.-L. Mottas , author B. Hildebrand , author T. Jaouen , author T. K. Kim , author S. Mukherjee , et al. , journal Communications Materials volume 2 , pages 1 ( year 2021 )

    work page 2021

  3. [3]

    Hsu , author A

    author Y.-T. Hsu , author A. Vaezi , author M. H. Fischer , and author E.-A. Kim , journal Nature communications volume 8 , pages 1 ( year 2017 )

    work page 2017

  4. [4]

    Ribak , author R

    author A. Ribak , author R. M. Skiff , author M. Mograbi , author P. Rout , author M. Fischer , author J. Ruhman , author K. Chashka , author Y. Dagan , and author A. Kanigel , journal Science advances volume 6 , pages eaax9480 ( year 2020 )

    work page 2020

  5. [5]

    von Rohr , author J.-C

    author F. von Rohr , author J.-C. Orain , author R. Khasanov , author C. Witteveen , author Z. Shermadini , author A. Nikitin , author J. Chang , author A. Wieteska , author A. Pasupathy , author M. Hasan , et al. , journal Science advances volume 5 , pages eaav8465 ( year 2019 )

    work page 2019

  6. [6]

    Guguchia , author F

    author Z. Guguchia , author F. von Rohr , author Z. Shermadini , author A. T. Lee , author S. Banerjee , author A. Wieteska , author C. Marianetti , author B. Frandsen , author H. Luetkens , author Z. Gong , et al. , journal Nature communications volume 8 , pages 1 ( year 2017 )

    work page 2017

  7. [7]

    Leng , author C

    author H. Leng , author C. Paulsen , author Y. K. Huang , and author A. de Visser , journal Phys. Rev. B volume 96 , pages 220506 ( year 2017 )

    work page 2017

  8. [8]

    author O. J. Clark , author M. J. Neat , author K. Okawa , author L. Bawden , author I. Markovi c \' c , author F. Mazzola , author J. Feng , author V. Sunko , author J. M. Riley , author W. Meevasana , et al. , journal Phys. Rev. Lett. volume 120 , pages 156401 ( year 2018 )

    work page 2018

  9. [9]

    Bahramy , author O

    author M. Bahramy , author O. Clark , author B.-J. Yang , author J. Feng , author L. Bawden , author J. Riley , author I. Markovi \'c , author F. Mazzola , author V. Sunko , author D. Biswas , et al. , journal Nature materials volume 17 , pages 21 ( year 2018 )

    work page 2018

  10. [10]

    Noh , author J

    author H.-J. Noh , author J. Jeong , author E.-J. Cho , author K. Kim , author B. I. Min , and author B.-G. Park , journal Phys. Rev. Lett. volume 119 , pages 016401 ( year 2017 )

    work page 2017

  11. [11]

    Leng , author J.-C

    author H. Leng , author J.-C. Orain , author A. Amato , author Y. K. Huang , and author A. de Visser , journal Phys. Rev. B volume 100 , pages 224501 ( year 2019 a )

    work page 2019

  12. [12]

    Salis , author P

    author M. Salis , author P. Rodi \`e re , author H. Leng , author Y. Huang , and author A. de Visser , journal Journal of Physics: Condensed Matter volume 30 , pages 505602 ( year 2018 )

    work page 2018

  13. [13]

    Sirohi , author S

    author A. Sirohi , author S. Das , author P. Adhikary , author R. R. Chowdhury , author A. Vashist , author Y. Singh , author S. Gayen , author T. Das , and author G. Sheet , journal Journal of Physics: Condensed Matter volume 31 , pages 085701 ( year 2019 )

    work page 2019

  14. [14]

    Das , author Amit , author A

    author S. Das , author Amit , author A. Sirohi , author L. Yadav , author S. Gayen , author Y. Singh , and author G. Sheet , journal Phys. Rev. B volume 97 , pages 014523 ( year 2018 a )

    work page 2018

  15. [15]

    Le , author L

    author T. Le , author L. Yin , author Z. Feng , author Q. Huang , author L. Che , author J. Li , author Y. Shi , and author X. Lu , journal Phys. Rev. B volume 99 , pages 180504 ( year 2019 )

    work page 2019

  16. [16]

    Liu , author C

    author Q. Liu , author C. Chen , author T. Zhang , author R. Peng , author Y.-J. Yan , author C.-H.-P. Wen , author X. Lou , author Y.-L. Huang , author J.-P. Tian , author X.-L. Dong , et al. , journal Phys. Rev. X volume 8 , pages 041056 ( year 2018 )

    work page 2018

  17. [17]

    Zhang , author K

    author P. Zhang , author K. Yaji , author T. Hashimoto , author Y. Ota , author T. Kondo , author K. Okazaki , author Z. Wang , author J. Wen , author G. Gu , author H. Ding , et al. , journal Science volume 360 , pages 182 ( year 2018 )

    work page 2018

  18. [18]

    author M. V. Salis , author J. P. Lorenz , author Y. K. Huang , and author A. de Visser , journal Phys. Rev. B volume 105 , pages 054508 ( year 2022 )

    work page 2022

  19. [19]

    Suter and author B

    author A. Suter and author B. Wojek , journal Physics Procedia volume 30 , pages 69 ( year 2012 )

    work page 2012

  20. [20]

    author Amit , author R. K. Singh , author N. Wadehra , author S. Chakraverty , and author Y. Singh , journal Phys. Rev. Materials volume 2 , pages 114202 ( year 2018 )

    work page 2018

  21. [21]

    Leng , author A

    author H. Leng , author A. Ohmura , author L. Anh , author F. Ishikawa , author T. Naka , author Y. Huang , and author A. De Visser , journal Journal of Physics: Condensed Matter volume 32 , pages 025603 ( year 2019 b )

    work page 2019

  22. [22]

    Luetkens , author H.-H

    author H. Luetkens , author H.-H. Klauss , author R. Khasanov , author A. Amato , author R. Klingeler , author I. Hellmann , author N. Leps , author A. Kondrat , author C. Hess , author A. K\"ohler , et al. , journal Phys. Rev. Lett. volume 101 , pages 097009 ( year 2008 )

    work page 2008

  23. [23]

    Khasanov , author R

    author R. Khasanov , author R. Gupta , author D. Das , author A. Amon , author A. Leithe-Jasper , and author E. Svanidze , journal Phys. Rev. Research volume 2 , pages 023142 ( year 2020 a )

    work page 2020

  24. [24]

    Khasanov , author D

    author R. Khasanov , author D. Das , author D. J. Gawryluk , author R. Gupta , and author C. Mielke , journal Phys. Rev. B volume 104 , pages L100508 ( year 2021 )

    work page 2021

  25. [25]

    Singh , author P

    author D. Singh , author P. K. Biswas , author S. Yoon , author C. Lee , author A. Hillier , author R. Singh , author A. Y. Singh , and author K.-Y. Choi , journal arXiv preprint arXiv:1910.13773 ( year 2019 )

    work page arXiv 1910

  26. [26]

    author E. H. Brandt , journal Phys. Rev. B volume 68 , pages 054506 ( year 2003 )

    work page 2003

  27. [27]

    Das , author D

    author D. Das , author D. T. Adroja , author M. R. Lees , author R. W. Taylor , author Z. S. Bishnoi , author V. K. Anand , author A. Bhattacharyya , author Z. Guguchia , author C. Baines , author H. Luetkens , et al. , journal Phys. Rev. B volume 103 , pages 144516 ( year 2021 a )

    work page 2021

  28. [28]

    Khasanov , author R

    author R. Khasanov , author R. Gupta , author D. Das , author A. Leithe-Jasper , and author E. Svanidze , journal Phys. Rev. B volume 102 , pages 014514 ( year 2020 b )

    work page 2020

  29. [29]

    Carrington and author F

    author A. Carrington and author F. Manzano , journal Physica C: Superconductivity volume 385 , pages 205 ( year 2003 ), ISSN issn 0921-4534

    work page 2003

  30. [30]

    Gupta , author C

    author R. Gupta , author C. L\"ohnert , author C. Wang , author D. Johrendt , author H. Luetkens , author S. Malick , author T. Shiroka , author Z. Hossain , and author R. Khasanov , journal Phys. Rev. B volume 102 , pages 144515 ( year 2020 )

    work page 2020

  31. [31]

    Gupta , author T

    author R. Gupta , author T. P. Ying , author Y. P. Qi , author H. Hosono , and author R. Khasanov , journal Phys. Rev. B volume 103 , pages 174511 ( year 2021 )

    work page 2021

  32. [32]

    Das , author R

    author D. Das , author R. Gupta , author A. Bhattacharyya , author P. K. Biswas , author D. T. Adroja , and author Z. Hossain , journal Phys. Rev. B volume 97 , pages 184509 ( year 2018 b )

    work page 2018

  33. [33]

    Gupta , author D

    author R. Gupta , author D. Das , author C. H. Mielke III , author Z. Guguchia , author T. Shiroka , author C. Baines , author M. Bartkowiak , author H. Luetkens , author R. Khasanov , author Q. Yin , et al. , journal npj Quantum Materials volume 7 , pages 1 ( year 2022 )

    work page 2022

  34. [34]

    Anemone , author C

    author G. Anemone , author C. A. P. , author G. M. , author C. F. , author A. T. A. , author K. C. , author S. L. C. , author P. A. , author L. V. de Parga A. , author B. G. , et al. , journal npj 2D Mater Appl volume 5 ( year 2021 )

    work page 2021

  35. [35]

    Das , author R

    author D. Das , author R. Gupta , author C. Baines , author H. Luetkens , author D. Kaczorowski , author Z. Guguchia , and author R. Khasanov , journal Phys. Rev. Lett. volume 127 , pages 217002 ( year 2021 b )

    work page 2021

  36. [36]

    author Y. J. Uemura , author L. P. Le , author G. M. Luke , author B. J. Sternlieb , author W. D. Wu , author J. H. Brewer , author T. M. Riseman , author C. L. Seaman , author M. B. Maple , author M. Ishikawa , et al. , journal Phys. Rev. Lett. volume 68 , pages 2712 ( year 1992 )

    work page 1992

  37. [37]

    author Y. J. Uemura , author V. J. Emery , author A. R. Moodenbaugh , author M. Suenaga , author D. C. Johnston , author A. J. Jacobson , author J. T. Lewandowski , author J. H. Brewer , author R. F. Kiefl , author S. R. Kreitzman , et al. , journal Phys. Rev. B volume 38 , pages 909 ( year 1988 )

    work page 1988