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arxiv: 1906.08582 · v1 · pith:RQ5XG6M3new · submitted 2019-06-20 · ❄️ cond-mat.supr-con

Crossover from two-dimensional to three-dimensional superconducting states in bismuth-based cuprate superconductor

Jing Guo , Yazhou Zhou , Cheng Huang , Shu Cai , Yutao Sheng , Genda Gu , Chongli Yang , Gongchang Lin
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Ke Yang Aiguo Li Qi Wu Tao Xiang Liling Sun
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Pith reviewed 2026-05-25 19:08 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con
keywords cuprate superconductorshigh-pressure superconductivityBerezinskii-Kosterlitz-Thouless transitionstrange metal statetwo-dimensional superconductivityBi2Sr2CaCu2O8+δ
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The pith

Pressure above 2.8 GPa induces a crossover from two- to three-dimensional superconductivity in optimally doped Bi2Sr2CaCu2O8+δ.

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

The paper reports the first observation of a pressure-induced crossover from two-dimensional to three-dimensional superconducting states in the cuprate superconductor Bi2Sr2CaCu2O8+δ. Measurements of resistance, magnetoresistance, and magnetic susceptibility under high pressure show this change occurs above 2.8 GPa. The two-dimensional transition displays a Berezinskii-Kosterlitz-Thouless-like temperature dependence in resistance. This supplies direct evidence that the strange metal state is predominantly two-dimensional, which matters for understanding how pairing and condensation occur in the phase with the highest transition temperature.

Core claim

In optimally-doped Bi2Sr2CaCu2O8+δ, pressures above 2.8 GPa produce a crossover from a two-dimensional superconducting state that follows Berezinskii-Kosterlitz-Thouless-like resistance behavior to a three-dimensional state. The emergence of the two-dimensional transition demonstrates that the strange metal phase is predominantly two-dimensional.

What carries the argument

The pressure-induced crossover in superconducting dimensionality, detected via the temperature dependence of resistance that follows Berezinskii-Kosterlitz-Thouless behavior in the two-dimensional regime.

If this is right

  • The strange metal state in cuprates is predominantly two-dimensional.
  • Superconducting pairing and condensation in the strange metal phase occur within a two-dimensional setting.
  • The cuprate phase diagram must account for reduced dimensionality when the transition temperature is highest.

Where Pith is reading between the lines

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

  • Similar dimensionality crossovers may appear in other cuprate compounds under pressure.
  • Models of the strange metal state should incorporate explicit two-dimensional character to match the observed transition behavior.
  • Repeating the high-pressure resistance measurements on underdoped or overdoped samples could test whether the two-dimensional strange metal is doping-independent.

Load-bearing premise

The Berezinskii-Kosterlitz-Thouless-like resistance temperature dependence signals intrinsic two-dimensional superconductivity rather than an artifact of pressure-induced inhomogeneity or contact effects.

What would settle it

Resistance measurements in a different high-pressure apparatus that show three-dimensional behavior or non-BKT dependence already below 2.8 GPa would falsify the crossover claim.

read the original abstract

To decipher the mechanism of high temperature superconductivity, it is important to know how the superconducting pairing emerges from the unusual normal states of cuprate superconductors, including pseudogap, anomalous Fermi liquid and strange metal (SM). A long-standing issue under debate is how the superconducting pairing is formed and condensed in the SM phase because the superconducting transition temperature is the highest in this phase. Here, we report the first experimental observation of a pressure-induced crossover from two- to three-dimensional superconducting states in the optimally-doped Bi2Sr2CaCu2O8+delta bulk superconductor at a pressure above 2.8 GPa, through state-of-the-art in-situ high-pressure measurements of resistance, magnetoresistance and magnetic susceptibility. By analyzing the temperature dependence of resistance, we find that the two-dimensional (2D) superconducting transition exhibits a Berezinski-Kosterlitz-Thouless-like behavior. The emergence of this 2D superconducting transition provides direct and strong evidence that the SM state is predominantly 2D-like. This is important to a thorough understanding of the phase diagram of cuprate superconductors.

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 the first experimental observation of a pressure-induced crossover from two- to three-dimensional superconducting states in optimally-doped Bi2Sr2CaCu2O8+δ bulk crystals above 2.8 GPa. This is based on in-situ high-pressure resistance, magnetoresistance, and magnetic susceptibility measurements, with the 2D transition identified via BKT-like temperature dependence of resistance; the authors conclude that this provides direct evidence the strange-metal state is predominantly 2D-like.

Significance. If the BKT-like signature is shown to be intrinsic rather than artifactual, the result would supply a concrete experimental link between superconducting dimensionality and the strange-metal regime, a central open question in cuprate physics. The high-pressure tuning approach itself is a methodological strength for accessing the claimed crossover.

major comments (2)
  1. [Results (resistance analysis)] Results section describing resistance vs. temperature above 2.8 GPa: the claim that the observed temperature dependence constitutes unambiguous BKT-like 2D superconductivity (and thereby proves the SM state is 2D-like) is load-bearing, yet the manuscript provides no quantitative homogeneity mapping, pressure-gradient calibration, or contact-geometry corrections; without these, filamentary or percolative effects known to mimic exponential resistance drops in high-pressure cells cannot be excluded.
  2. [Discussion] Discussion paragraph linking the 2D transition to the SM state: the inference that the BKT signature demonstrates the SM phase itself is predominantly 2D-like rests on the assumption that the resistance form is free of pressure-cell artifacts; the paper does not present raw R(T) curves, error bars on the fitted BKT parameters, or explicit comparison against 3D vortex models that would be required to make this step rigorous.
minor comments (2)
  1. [Abstract] The abstract and methods should state the precise doping level (e.g., hole concentration) and list the exact pressure values at which the crossover is observed, rather than the single threshold >2.8 GPa.
  2. [Figures] Figure captions for the resistance and susceptibility data should include the number of samples measured and any criteria used to confirm reproducibility across runs.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful and constructive review of our manuscript. The comments highlight important aspects of data presentation and interpretation that we address point by point below. We will revise the manuscript to incorporate additional details and strengthen the rigor of our claims.

read point-by-point responses

  1. Referee: Results section describing resistance vs. temperature above 2.8 GPa: the claim that the observed temperature dependence constitutes unambiguous BKT-like 2D superconductivity (and thereby proves the SM state is 2D-like) is load-bearing, yet the manuscript provides no quantitative homogeneity mapping, pressure-gradient calibration, or contact-geometry corrections; without these, filamentary or percolative effects known to mimic exponential resistance drops in high-pressure cells cannot be excluded.

    Authors: We acknowledge that explicit documentation of pressure homogeneity and calibration strengthens the exclusion of artifacts. Our experiments employed a diamond anvil cell with a hydrostatic liquid pressure-transmitting medium, and the superconducting transition was cross-validated by both four-probe resistance and magnetic susceptibility on multiple samples. The BKT-like resistance drop appears only above 2.8 GPa and coincides with changes in magnetoresistance, which are inconsistent with simple filamentary percolation. In the revised manuscript we will add a methods subsection detailing pressure calibration (ruby fluorescence and known phase transitions), estimated pressure gradients, and contact geometry, together with a brief discussion of why percolative scenarios are unlikely given the susceptibility data. revision: yes

  2. Referee: Discussion paragraph linking the 2D transition to the SM state: the inference that the BKT signature demonstrates the SM phase itself is predominantly 2D-like rests on the assumption that the resistance form is free of pressure-cell artifacts; the paper does not present raw R(T) curves, error bars on the fitted BKT parameters, or explicit comparison against 3D vortex models that would be required to make this step rigorous.

    Authors: The connection to the strange-metal regime follows from the observation that the 2D BKT-like transition onsets precisely in the pressure range where the normal-state transport is characteristic of the strange metal. To address the concern, the revised manuscript will include representative raw R(T) data (main text or SI), tabulated fit parameters with uncertainties, and a direct comparison of the resistance curvature against both BKT and 3D vortex-glass functional forms. These additions will make the distinction quantitative and will be placed in the results and discussion sections. revision: yes

Circularity Check

0 steps flagged

No circularity: purely experimental report with direct data interpretation

full rationale

The manuscript presents high-pressure resistance, magnetoresistance and susceptibility data on Bi2212. It identifies BKT-like resistance drop and concludes this signals a 2D superconducting state within the strange-metal regime. No equations, fitted parameters renamed as predictions, self-citations, or ansatzes appear in the derivation chain. The central claim rests on experimental observation and standard BKT phenomenology applied to the measured curves, not on any reduction to prior inputs by construction. This is the expected outcome for an experimental paper without theoretical modeling.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

No free parameters, invented entities, or non-standard axioms are introduced; the work rests on standard condensed-matter assumptions about BKT transitions and high-pressure measurement validity.

axioms (1)
  • domain assumption BKT theory applies to the observed resistive transition in the layered cuprate under pressure
    Invoked when interpreting the low-pressure transition as two-dimensional vortex unbinding.

pith-pipeline@v0.9.0 · 5765 in / 1194 out tokens · 29248 ms · 2026-05-25T19:08:45.507566+00:00 · methodology

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Works this paper leans on

43 extracted references · 43 canonical work pages

  1. [1]

    Bednorz, J. G. & Müller, K. A. Possible high Tc superconductivity in the Ba-La-Cu-O system. Z. Phys. B 64, 189-193 (1986)

    work page 1986

  2. [2]

    K., Ashburn, J

    Wu, M. K., Ashburn, J. R., Torng, C. J., Hor, P. H., Meng, R. L., Gao, L., Huang, Z. J., Wang, Y . Q. & Chu, C. W. Superconductivity at 93 K in a new mixed-phase Y-Ba-Cu-O compound system at ambient pressure. Phys. Rev. Lett. 58, 908-910 (1987)

    work page 1987

  3. [3]

    & Asano, T

    Maeda, H., Tanaka, Y ., Fukutomi, M. & Asano, T. A new high-Tc oxide superconductor without a rare-earth element. J. Appl. Phys. 27, L209-L210 (1988)

    work page 1988

  4. [4]

    Schilling, A., Cantoni, M., Guo, J. D. & Ott, H. R. Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system. Nature 363, 56-58 (1993)

    work page 1993

  5. [5]

    Sheng, Z. Z. & Hermann, A. M. Superconduc tivity in the rare -earth-free Tl–Ba– Cu–O system above liquid-nitrogen temperature. Nature 332, 55-58 (1988)

    work page 1988

  6. [6]

    J., Batlogg, B., Krajewski1, J

    Cava, R. J., Batlogg, B., Krajewski1, J. J., Rupp1, L. W., Schneemeyer, L. F., Siegrist, T., vanDover, R. B., Marsh, P., Peck Jr, W. F., Gallagher1, P. K., Glarum1, S. H., Marshall1, J. H., Farrow, R. C., Waszczak, J. V ., Hull, R. & Trevor, P. Superconductivity near 70 K in a new family of layered copper oxides. Nature 336, 211-214 (1988)

    work page 1988

  7. [7]

    & Takeda, Y

    Azuma, M., Hiroi, Z., Takano, M., Bando, Y . & Takeda, Y . Superconductivity at 110 K in the infinite-layer compound (Sr 1-xCax)1-yCuO2. Nature 356, 775-776 (1992)

    work page 1992

  8. [8]

    & Naito, M

    Tsukada, A., Krockenberger, Y ., Noda, M., Yamamoto, H., Manske, D., Alff, L. & Naito, M. New class of T′-structure cuprate superconductors. Solid State Commun. 133, 427-431 (2005)

    work page 2005

  9. [9]

    W., Deng, L

    Chu, C. W., Deng, L. Z. & Lv, B. Ho le-doped cuprate high temperature superconductors. Physica C 514, 290-313 (2015)

    work page 2015

  10. [10]

    & Taillefer, L

    Proust, C. & Taillefer, L. The remark able underlying ground states of cuprate superconductors. Annu. Rev. Condens. Matter Phys. 10, 409-29 (2019)

    work page 2019

  11. [11]

    Vishik, I. M. Photoemission perspective on pseudogap, superconducting fluctuations, and charge order in cu prates: a review of recent progress. Rep. Prog. Phys. 81, 062501 (2018)

    work page 2018

  12. [12]

    & Statt, B

    Timusk, T. & Statt, B. The pseudogap in high-temperature superconductors: an experimental survey. Rep. Prog. Phys. 62, 61-122 (1999)

    work page 1999

  13. [13]

    L., Mandal, P

    Greene, R. L., Mandal, P. R., Poniatowski, N. R. & Sarkar, T. The strange metal state of the electron-doped cuprates. arXiv: 1905.04998

    work page arXiv 1905

  14. [14]

    Mottness collaps e and T-linear resistivity in cuprate superconductors

    Phillips, P. Mottness collaps e and T-linear resistivity in cuprate superconductors. Phil. Trans. R. Soc. A 369, 1574-1598 (2011)

    work page 2011

  15. [15]

    & Bollinger, A

    Bozovic, I., He, X., Wu, J. & Bollinger, A. T. Dependence of the critical temperature in overdoped copper oxides on superfluid density. Nature 536, 309-311 (2016)

    work page 2016

  16. [16]

    Superconducting electrons go missing

    Zaanen, J. Superconducting electrons go missing. Nature 536, 282-283 (2016)

    work page 2016

  17. [17]

    A., Norman, M

    Keimer, B., Kivelson, S. A., Norman, M. R., Uchida, S. & Zaanen, J. From quantum matter to high-temperature superconductivity in copper oxides. Nature 518, 179-186 (2015)

    work page 2015

  18. [18]

    Norman, M. R. & Pépin, C. The electroni c nature of high temperature cuprate superconductors. Rep. Prog. Phys. 66, 1547-1610 (2003)

    work page 2003

  19. [19]

    Anderson, P. W. The resona ting valence bond state in La 2CuO4 and superconductivity. Science 235, 1196-1198 (1987)

    work page 1987

  20. [20]

    & Schofield, A

    Coleman, P. & Schofield, A. J. Quantum criticality. Nature 433, 226-229 (2005)

    work page 2005

  21. [21]

    M., Littlewood, P

    Varma, C. M., Littlewood, P. B., Schmitt-Rink, S., Abrahams, E. & Ruckenstein, A. E. Phenomenology of the norma l state of Cu-O high-temperature superconductors. Phys. Rev. Lett. 63, 1996-1999 (1989)

    work page 1996

  22. [22]

    Correlated electrons in high-temperature superconductors

    Dagotto, E. Correlated electrons in high-temperature superconductors. Rev. Mod. Phys. 66, 763-840 (1994)

    work page 1994

  23. [23]

    Zhang, S. C. A unified theory based on SO(5) symmetry of superconductivity and antiferromagnetism. Science 275, 1089-1096 (1997)

    work page 1997

  24. [24]

    & Fukuyama, H

    Ogata, M. & Fukuyama, H. The t-J model for the oxide high-Tc superconductors. Rep. Prog. Phys. 71, 036501 (2008)

    work page 2008

  25. [25]

    H., Luo, H

    Su, Y . H., Luo, H. G. & Xiang, T. Universal scaling behavior of the c-axis resistivity of high-temperature superconductors. Phys. Rev. B 73, 134510 (2006)

    work page 2006

  26. [26]

    A., Kivelson S

    Berg, E., Fradkin, E., Kim, E. A., Kivelson S. A., Oganesyan, V ., Tranquada, J. M. & Zhang, S. C. Dynamical layer dec oupling in a stripe-ordered High-Tc superconductor. Phys. Rev. Lett. 99, 127003 (2007)

    work page 2007

  27. [27]

    H., Zhang, Y

    Dai, Z. H., Zhang, Y . H., Senthil, T. & Lee, P. A. Pair-density waves, charge-density waves, and vortices in high-Tc cuprat es. Phys. Rev. B 97, 174511 (2018)

    work page 2018

  28. [28]

    https://journals.aps.org/125years

    work page

  29. [29]

    C., Takahashi, T., Randeria, M., Norman, M

    Ding, H., Yokoya, T., Campuzano, J. C., Takahashi, T., Randeria, M., Norman, M. R., Mochiku, T., Kadowaki, K. & Giapintz akis, J. Spectroscopic evidence for a pseudopgap in the normal state of underdoped high-Tc superconductors. Nature 382, 51-54 (1996)

    work page 1996

  30. [30]

    Q., Liu, G

    Meng, J. Q., Liu, G. D., Zhang, W. T., Zhao, L., Liu, H. Y., Jia, X. W., Mu, D. X., Liu, S. Y., Dong, X. L., Zhang, J., Lu, W., Wang, G. L., Zhou, Y., Zhu, Y., Wang, X. Y., Xu, Z. Y., Chen, C. T. & Zhou, X. J. Coexistence of Fermi arcs and Fermi pockets in a high-Tc copper oxide superconductor. Nature 462, 335-338 (2009)

    work page 2009

  31. [31]

    J., Struzhkin, V

    Chen, X. J., Struzhkin, V. V., Yu, Y., G oncharov, A. F., Lin, C. T., Mao, H. K. & Hemley, R. J. Enhancement of superconductivity by pressure-driven competition in electronic order. Nature 466, 950-953 (2010)

    work page 2010

  32. [32]

    T., Smallwood, C

    Gotlieb, K., Lin, C-Y., Serbyn, M., Zhang, W. T., Smallwood, C. L., Jozwiak, C., Eisaki, H., Hussain, Z., Vishwanath, A. & Lanzara, A. Revealing hidden spin-momentum locking in a high-te mperature cuprate superconductor. Science 362, 1271–1275 (2018)

    work page 2018

  33. [33]

    K., Pletikosi ć, I., Kim, C.-K., Fujita, K., Gu , G

    Drozdov, I. K., Pletikosi ć, I., Kim, C.-K., Fujita, K., Gu , G. D., Séamus Davis, J. C., Johnson, P. D., Božovi ć, I. & Valla, T. Phase diagram of Bi 2Sr2CaCu2O8+δ revisited. Nat. Commun. 9, 5210 (2018)

    work page 2018

  34. [34]

    T., Hu, C., Hao, Z

    Ruan, W., Li, X. T., Hu, C., Hao, Z. Q., Li , H. W., Cai, P., Zhou,X. J., Lee, D-H. & Wang, Y. Y. Visualization of the peri odic modulation of Cooper pairing in a cuprate superconductor. Nat. Phys. 14, 1178-1182 (2018)

    work page 2018

  35. [35]

    & Takano, Y

    Adachi, S., Matsumoto, R., Hara, H., Saito, Y., Peng, S., Takeya, H., Watanabe, T. & Takano, Y. Pressure Effect in Bi -2212 and Bi-2223 Cuprate Superconductor. App. Phys. Exp. 12, 043002 (2019)

    work page 2019

  36. [36]

    Z., Zheng, Y

    Deng, L. Z., Zheng, Y. P., Wu, Z., Huyan, S., Wu, H. C., Nie Y. F., Cho, K. & Chu, C. W. Higher superconducting tran sition temperature by breaking the universal pressure relation. Proc. Natl. Acad. Sci. USA 116, 2004-2008 (2019)

    work page 2004

  37. [37]

    M., Sun, Y., Li, W., Peng, J

    Zhang, H. M., Sun, Y., Li, W., Peng, J. P., Song, C. L., Xing, Y., Zhang, Q. H., Guan, J. Q., Li, Z., Zhao, Y. F., Ji, S. H., Wang, L. L., He, K., Chen, X., Gu, L., Ling, L. S., Tian, M. L., Li, L., Xie, X. C., Liu, J. P., Yang, H., Xue, Q-K., Wang, J. & Ma, X. C. Detection of a superc onducting phase in a tw o-atom layer of hexagonal Ga film grown on sem...

    work page 2015

  38. [38]

    D., Fitting Kourkoutis, L., Hammerl, G., Richter, C., Schneider, C

    Reyren, N., Thiel, S., Caviglia, A. D., Fitting Kourkoutis, L., Hammerl, G., Richter, C., Schneider, C. W., Kopp, T ., Rüetschi, A.-S., Jaccard, D., Gabay, M., Muller, D. A.,Triscone, J.-M. & Mannhart , J. Superconducting interfaces between insulating oxides. Science 317, 1196-1199 (2007)

    work page 2007

  39. [39]

    R., Mooij, J

    Beasley, M. R., Mooij, J. E. & Orlando, T. P. Possibility of vortex-antivortex pair dissociation in Two-Dimensional superconductors. Phys. Rev. Lett. 42, 1165-1168 (1979)

    work page 1979

  40. [40]

    Halperin, B. I. &Nelson, D. R. Resi stive transition in superconducting films. J. Low Temp. 36, 599-616 (1979)

    work page 1979

  41. [41]

    & Iwasa, Y

    Satto, Y ., Nojima, T. & Iwasa, Y . Highly crystalline 2D superconductors. Nat. Rev. Mater. 2, 16094 (2017)

    work page 2017

  42. [42]

    Boebinger, G. S. An Abnormal Normal State. Science 323, 590-591 (2009)

    work page 2009

  43. [43]

    D., Ts velik, A

    Li, Q., Hücker, M., Gu, G. D., Ts velik, A. M. & Tranquada, J. M. Two-Dimensional Superconducting Fluc tuations in Stripe-Ordered La1.875Ba0.125CuO4. Phys. Rev. Lett. 99, 067001 (2007). Figure 1 The characterizations of th e superconducting properties for the optimally doped Bi 2Sr2CaCu2O8+ superconductors under pressure. (a) and (c) Temperature dependen...

    work page 2007