Abstract
Atomically thin van der Waals crystals epitomize ideal material systems in the two-dimensional (2D) limit. This reduction in dimensionality often leads to important consequences, best exemplified by the emergence of new physics in graphene and other 2D materials that can be readily tuned by gating1,2. Vast opportunities arise in extending this top-down approach to other material systems. Recent experiments have demonstrated that the essential physics of high-temperature superconductivity in cuprates is contained within just two CuO2 planes3. Here we push dimensionality reduction to the extreme by examining a single layer of Bi2Sr2CuO6+δ (Bi-2201), which comprises only one CuO2 plane. In this ultimate 2D limit, we observe a robust dimensionality effect that manifests as an approximately 10% reduction in the optimal superconducting transition temperature. Moreover, this reduction in dimensionality offers unprecedented tunability—we successfully extended the phase diagram of Bi-2201 into uncharted territories via finely controlled oxygenation of single-monolayer specimens. Leveraging this tunability, we discovered that an anomalous metal state emerges between the insulating and superconducting states as the temperature approaches zero. Concurrently, we observe an anomalous scaling behaviour characterized by a divergent critical exponent. These findings illuminate the nature of the superconductor-to-insulator quantum phase transition in cuprates.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$32.99 / 30 days
cancel any time
Subscribe to this journal
Receive 52 print issues and online access
$199.00 per year
only $3.83 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to the full article PDF.
USD 39.95
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
The datasets generated and analysed during the current study are available from the corresponding authors upon request.
References
Novoselov, K. S. et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature 438, 197–200 (2005).
Zhang, Y., Tan, Y., Stormer, H. L. & Kim, P. Experimental observation of the quantum Hall effect and Berry’s phase in graphene. Nature 438, 201–204 (2005).
Yu, Y. et al. High-temperature superconductivity in monolayer Bi2Sr2CaCu2O8+δ. Nature 575, 156–163 (2019).
Bednorz, J. G. & Müller, K. A. Possible high Tc superconductivity in the Ba–La–Cu–O system. Z. Phys. B 64, 189–193 (1986).
Kamihara, Y., Watanabe, T., Hirano, M. & Hosono, H. Iron-based layered superconductor La[O1−xFx]FeAs (x = 0.05–0.12) with Tc = 26 K. J. Am. Chem. Soc. 130, 3296–3297 (2008).
Li, D. et al. Superconductivity in an infinite-layer nickelate. Nature 572, 624–627 (2019).
Mermin, N. D. & Wagner, H. Absence of ferromagnetism or antiferromagnetism in one-or two-dimensional isotropic Heisenberg models. Phys. Rev. Lett. 17, 1133 (1966).
Kosterlitz, J. M. & Thouless, D. J. Ordering, metastability and phase transitions in two-dimensional systems. J. Phys. C 6, 1181 (1973).
Jiang, D. et al. High-Tc superconductivity in ultrathin Bi2Sr2CaCu2O8+x down to half-unit-cell thickness by protection with graphene. Nat. Commun. 5, 5708 (2014).
Sterpetti, E., Biscaras, J., Erb, A. & Shukla, A. Comprehensive phase diagram of two-dimensional space charge doped Bi2Sr2CaCu2O8+x. Nat. Commun. 8, 2060 (2017).
Liao, M. et al. Superconductor–insulator transitions in exfoliated Bi2Sr2CaCu2O8+δ flakes. Nano Lett. 18, 5660–5665 (2018).
Zhao, S. F. et al. Sign-reversing Hall effect in atomically thin high-temperature Bi2.1Sr1.9CaCu2.0O8+δ superconductors. Phys. Rev. Lett. 122, 247001 (2019).
Pickett, W. E. Electronic structure of the high-temperature oxide superconductors. Rev. Mod. Phys. 61, 433 (1989).
Feng, D. L. et al. Bilayer splitting in the electronic structure of heavily overdoped Bi2Sr2CaCu2O8+δ. Phys. Rev. Lett. 86, 5550 (2001).
Chuang, Y. et al. Doubling of the bands in overdoped Bi2Sr2CaCu2O8+δ: evidence for c-axis bilayer coupling. Phys. Rev. Lett. 87, 117002 (2001).
Bogdanov, P. V. et al. Photoemission study of Pb doped Bi2Sr2CaCu2O8: a Fermi surface picture. Phys. Rev. B 64, 180505 (2001).
Luo, X. et al. Electronic origin of high superconducting critical temperature in trilayer cuprates. Nat. Phys. 19, 1841–1847 (2023).
Fujita, K. et al. Effect of disorder outside the CuO2 planes on Tc of copper oxide superconductors. Phys. Rev. Lett. 95, 97006 (2005).
Boyer, M. C. et al. Imaging the two gaps of the high-temperature superconductor Bi2Sr2CuO6+x. Nat. Phys. 3, 802–806 (2007).
He, Y. et al. Fermi surface and pseudogap evolution in a cuprate superconductor. Science 344, 608–611 (2014).
Webb, T. A. et al. Density wave probes cuprate quantum phase transition. Phys. Rev. X 9, 21021 (2019).
Bollinger, A. T. et al. Superconductor–insulator transition in La2−xSrxCuO4 at the pair quantum resistance. Nature 472, 458–460 (2011).
Leng, X. et al. Electrostatic control of the evolution from a superconducting phase to an insulating phase in ultrathin YBa2Cu3O7−x films. Phys. Rev. Lett. 107, 27001 (2011).
Konstantinovi C, Z., Li, Z. Z. & Raffy, H. Temperature dependence of the Hall effect in single-layer and bilayer Bi2Sr2Can−1CunOy thin films at various oxygen contents. Phys. Rev. B 62, R11989 (2000).
Kleiner, R. & Müller, P. Intrinsic Josephson effects in high-Tc superconductors. Phys. Rev. B 49, 1327 (1994).
Wan, Y. M., Hebboul, S. E., Harris, D. C. & Garland, J. C. Interlayer Josephson coupling of thermally excited vortices in Bi2Sr2CaCu2O8−y. Phys. Rev. Lett. 71, 157 (1993).
Locquet, J. et al. Doubling the critical temperature of La1. 9Sr0. 1CuO4 using epitaxial strain. Nature 394, 453–456 (1998).
Fratini, M. et al. Scale-free structural organization of oxygen interstitials in La2CuO4+y. Nature 466, 841–844 (2010).
Poccia, N. et al. Spatially correlated incommensurate lattice modulations in an atomically thin high-temperature Bi2.1Sr1.9CaCu2.0O8+y superconductor. Phys. Rev. Mater. 4, 114007 (2020).
Sacépé, B., Feigel Man, M. & Klapwijk, T. M. Quantum breakdown of superconductivity in low-dimensional materials. Nat. Phys. 16, 734–746 (2020).
Lin, Y., Nelson, J. & Goldman, A. M. Superconductivity of very thin films: the superconductor–insulator transition. Physica C 514, 130–141 (2015).
Sondhi, S. L., Girvin, S. M., Carini, J. P. & Shahar, D. Continuous quantum phase transitions. Rev. Mod. Phys. 69, 315 (1997).
Garcia-Barriocanal, J. et al. Electronically driven superconductor–insulator transition in electrostatically doped La2CuO4+δ thin films. Phys. Rev. B 87, 24509 (2013).
Xing, Y. et al. Quantum Griffiths singularity of superconductor–metal transition in Ga thin films. Science 350, 542–545 (2015).
Phillabaum, B., Carlson, E. W. & Dahmen, K. A. Spatial complexity due to bulk electronic nematicity in a superconducting underdoped cuprate. Nat. Commun. 3, 915 (2012).
Del Maestro, A., Rosenow, B., M U Ller, M. & Sachdev, S. Infinite randomness fixed point of the superconductor–metal quantum phase transition. Phys. Rev. Lett. 101, 35701 (2008).
Hoyos, J. A., Kotabage, C. & Vojta, T. Effects of dissipation on a quantum critical point with disorder. Phys. Rev. Lett. 99, 230601 (2007).
Vojta, T., Farquhar, A. & Mast, J. Infinite-randomness critical point in the two-dimensional disordered contact process. Phys. Rev. E 79, 11111 (2009).
Wang, Z., Liu, Y., Ji, C. & Wang, J. Quantum phase transitions in two-dimensional superconductors: a review on recent experimental progress. Rep. Prog. Phys. 87, 14502 (2024).
Saito, Y., Nojima, T. & Iwasa, Y. Highly crystalline 2D superconductors. Nat. Rev. Mater. 2, 16094 (2017).
Liu, S. et al. Three-dimensional quantum Griffiths singularity in bulk iron-pnictide superconductors. Natl Sci. Rev. 11, nwae220 (2024).
Zhao, Q. et al. Isotropic quantum Griffiths singularity in Nd0.8Sr0.2NiO2 infinite-layer superconducting thin films. Phys. Rev. Lett. 133, 36003 (2024).
Liu, Y. et al. Anomalous quantum Griffiths singularity in ultrathin crystalline lead films. Nat. Commun. 10, 3633 (2019).
Gotlieb, K. et al. Revealing hidden spin-momentum locking in a high-temperature cuprate superconductor. Science 362, 1271–1275 (2018).
Kapitulnik, A., Kivelson, S. A. & Spivak, B. Colloquium: anomalous metals: failed superconductors. Rev. Mod. Phys. 91, 11002 (2019).
Zhang, X., Palevski, A. & Kapitulnik, A. Anomalous metals: from “failed superconductor” to “failed insulator”. Proc. Natl Acad. Sci. USA 119, e2092471177 (2022).
Fisher, M. P. Quantum phase transitions in disordered two-dimensional superconductors. Phys. Rev. Lett. 65, 923 (1990).
Phillips, P. & Dalidovich, D. The elusive Bose metal. Science 302, 243–247 (2003).
Das, D. & Doniach, S. Bose metal: gauge-field fluctuations and scaling for field-tuned quantum phase transitions. Phys. Rev. B 64, 134511 (2001).
Li, L. et al. Anomalous quantum metal in a 2D crystalline superconductor with electronic phase nonuniformity. Nano Lett. 19, 4126–4133 (2019).
Ye, P., Tian, C., Qi, X. & Weng, Z. Confinement-deconfinement interplay in quantum phases of doped Mott insulators. Phys. Rev. Lett. 106, 147002 (2011).
Kou, S. & Weng, Z. Topological gauge structure and phase diagram for weakly doped antiferromagnets. Phys. Rev. Lett. 90, 157003 (2003).
Spivak, B., Oreto, P. & Kivelson, S. A. Theory of quantum metal to superconductor transitions in highly conducting systems. Phys. Rev. B 77, 214523 (2008).
Kohsaka, Y. et al. An intrinsic bond-centered electronic glass with unidirectional domains in underdoped cuprates. Science 315, 1380–1385 (2007).
Fujita, K. et al. Spectroscopic imaging scanning tunneling microscopy studies of electronic structure in the superconducting and pseudogap phases of cuprate high-Tc superconductors. J. Phys. Soc. Jpn 81, 11005 (2011).
Fujita, K. et al. Simultaneous transitions in cuprate momentum-space topology and electronic symmetry breaking. Science 344, 612–616 (2014).
McElroy, K. et al. Relating atomic-scale electronic phenomena to wave-like quasiparticle states in superconducting Bi2Sr2CaCu2O8+δ. Nature 422, 592–596 (2003).
Tamir, I. et al. Sensitivity of the superconducting state in thin films. Sci. Adv. 5, eaau3826 (2019).
Acknowledgements
We thank D.-H. Lee, X. Lin, Y. Qi, J. Wang and C. Tang for helpful discussions. We also thank H. Eisaki, G. D. Gu, A. Haug, Z. Zhang, J. Shao and Y. Zhao for their help with the experiment. Part of the sample fabrication was conducted at Nano-fabrication Laboratory at Fudan University.
Funding
H.L., Y.Y., L.M., W.R. and Y.Z. acknowledge support from National Key R&D Program of China (grant number 2022YFA1403301), Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China (grant number JYB2025XDXM120), National Science Foundation of China (grant number 12350404), Quantum Science and Technology-National Science and Technology Major Project (grant number 2024ZD0300104), and Shanghai Municipal Science and Technology Commission (grant numbers 23JC1400600 and 2019SHZDZX01). W.R. acknowledges additional support from National Science Foundation of China (grant number 12274087) Shanghai Science and Technology Development Funds (grant number 22QA1400600). Y.Y. acknowledges addtional support from Shanghai Municipal Science and Technology Project (grant number 25DZ3008100). D. Song acknowledges support from the Max Planck-UBC-UTokyo Centre for Quantum Materials and the Canada First Research Excellence Fund, Quantum Materials and Future Technologies. P.C. acknowledges support from National Key R&D Program of China (grant number 2022YFA1403102), Quantum Science and Technology-National Science and Technology Major Project (grant number 2021ZD0302502), National Science Foundation of China (grant number 12074424), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China. Y.C, L.Z. and X.Z. acknowledge support from National Science Foundation of China (grant number 11888101). Z.W. acknowledges support from National Science Foundation of China (grant number 12347107) and National Key R&D Program of China (grant number 2021YFA1402101). X.H.C. acknowledges support from the National Science Foundation of China (grant numbers 11888101 and 11534010), the National Key R&D Program of China (grant numbers 2017YFA0303001 and 2016YFA0300201), Strategic Priority Research Program of the Chinese Academy of Sciences (grant number XDB25000000) and the Key Research Program of Frontier Sciences, CAS (grant number QYZDY-SSW-SLH021). This work has been supported by the New Cornerstone Science Foundation.
Author information
Authors and Affiliations
Contributions
Y.Z., W.R., X.H.C. and J.S. supervised the project. D. Song, R.Z., Y.C., L.Z. and X.Z. synthesized the bulk crystals. H.L., L.M. and P.C. fabricated STM devices and performed STM measurements. H.L. and Y.Y. fabricated transport devices. H.L. performed transport measurement. D. Shahar provided InOx thin films. H.L., Y.Y., Z.W., W.R. and Y.Z. analysed the data and wrote the paper with input from all authors.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature thanks Jianfeng Ge, Nicola Poccia and Boris Spivak for their contribution to the peer review of this work.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Figures (download DOCX )
This file contains Supplementary Figs. 1–25 and References.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Luo, H., Song, D., Yu, Y. et al. Superconducting 2D cuprate with a single CuO2 plane. Nature (2026). https://doi.org/10.1038/s41586-026-10857-1
Received:
Accepted:
Published:
Version of record:
DOI: https://doi.org/10.1038/s41586-026-10857-1