Antiferromagnetic Quantum Criticality in Infinite-Layer Cuprates Sr1-xNdxCuO2

Bin-Jie Wu; Can-Li Song; Da-Zhuang Deng; Guang-Ran Wei; Ji-Hai Zhang; Qi-Kun Xue; Qun Zhu; Xi Zhou; Xu-Cun Ma; Yong Zhong

arxiv: 2606.04559 · v1 · pith:VIV2RP7Bnew · submitted 2026-06-03 · ❄️ cond-mat.supr-con · cond-mat.mtrl-sci· cond-mat.str-el

Antiferromagnetic Quantum Criticality in Infinite-Layer Cuprates Sr1-xNdxCuO2

Bin-Jie Wu , Ze-Xian Deng , Guang-Ran Wei , Xi Zhou , Ji-Hai Zhang , Da-Zhuang Deng , Qun Zhu , Yong Zhong

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Can-Li Song Xu-Cun Ma Qi-Kun Xue

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Pith reviewed 2026-06-28 04:22 UTC · model grok-4.3

classification ❄️ cond-mat.supr-con cond-mat.mtrl-scicond-mat.str-el

keywords antiferromagnetic quantum criticalityinfinite-layer cupratesFermi surface reconstructionstrange metal behaviorelectron-doped cupratesHall transportspin-density-wave

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The pith

Infinite-layer cuprates exhibit an antiferromagnetic quantum critical point at doping xc approximately 0.155.

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

The paper uses high-quality thin films of the infinite-layer cuprate Sr1-xNdxCuO2 grown by ozone-assisted molecular beam epitaxy to study the electron-doped side of the cuprate phase diagram. Hall transport reveals a sharp carrier-type transition at xc ~ 0.155 that marks a Fermi surface reconstruction. This transition is quantitatively explained by a spin-density-wave tight-binding model, pointing to an antiferromagnetic origin. Near xc the normal state shows strange-metal resistivity persisting to 2 K when superconductivity is suppressed. These results indicate that antiferromagnetic quantum criticality is intrinsic and universal in electron-doped cuprates.

Core claim

The authors synthesize oxygen-stoichiometric infinite-layer cuprate thin films across the superconducting dome and measure Hall transport that shows a sharp carrier-type transition at xc ~ 0.155 signaling Fermi surface reconstruction. A spin-density-wave tight-binding model reproduces the transport evolution, supporting an antiferromagnetic origin of this quantum phase transition. Upon suppressing superconductivity with magnetic fields, the normal-state resistivity exhibits pristine strange metal behavior down to 2 K near xc. The findings establish an intrinsic, universal antiferromagnetic quantum criticality in electron-doped cuprates.

What carries the argument

Spin-density-wave tight-binding model that accounts for the doping evolution of Hall transport and identifies the antiferromagnetic origin of the Fermi surface reconstruction.

Load-bearing premise

The thin films are free of apical oxygen instabilities and uncontrolled oxygen vacancies that plagued earlier studies.

What would settle it

If varying the oxygen content in the films independently moves the carrier transition doping or eliminates the strange metal behavior, that would indicate the effects are due to disorder rather than antiferromagnetic order.

read the original abstract

The interplay between quantum criticality and Fermi surface reconstruction is central to elucidating the phase diagram of high-temperature cuprate superconductors. While studies on electron-doped T'-structure cuprates suggest an antiferromagnetic origin of this reconstruction, quantitative consensus has been hindered by apical oxygen instabilities and uncontrolled oxygen vacancies. Here, we overcome these limitations by utilizing ozone-assisted molecular beam epitaxy to synthesize high-quality, oxygen-stoichiometric thin films of infinite-layer cuprate Sr1-xNdxCuO2 across its entire superconducting dome. Hall transport measurements reveal a sharp carrier-type transition signaling a Fermi surface reconstruction at a critical doping xc ~ 0.155. We show that a spin-density-wave tight-binding model quantitatively reproduces the transport evolution, supporting an antiferromagnetic origin of this quantum phase transition. Furthermore, upon suppressing superconductivity with magnetic fields, the normal-state resistivity exhibits a pristine strange metal behavior that persists down to 2 K in the vicinity of xc. Our findings establish an intrinsic, universal antiferromagnetic quantum criticality in electron-doped cuprates, positioning the structurally simplest infinite-layer cuprates as a clean benchmark platform for theories of unconventional superconductivity.

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 paper reports a Hall sign change at xc ~ 0.155 plus T-linear resistivity in ozone-MBE infinite-layer films, but the abstract leaves the oxygen-stoichiometry claim and the independence of the SDW fit unproven.

read the letter

The new piece is the observation of a carrier-type transition at xc ~ 0.155 in Sr1-xNdxCuO2 films made by ozone-assisted MBE, plus the claim of pristine strange-metal resistivity down to 2 K near that doping once superconductivity is suppressed. The synthesis route is presented as solving the apical-oxygen and vacancy problems that limited earlier T' work, which is a practical step forward if the films really are stoichiometric.

The SDW tight-binding model is said to reproduce the Hall evolution, which aligns with existing suggestions in the T' literature. If the model parameters come from band-structure calculations rather than being tuned to the transport data, that would give some independent support for an antiferromagnetic origin.

The soft spots sit where the abstract stops short. No fitting details, error bars, or raw curves are mentioned, so it is not possible to judge whether the SDW reproduction is quantitative or circular. The central assumption that residual apical oxygen and vacancies have been eliminated rests on the growth method alone; without explicit characterization in the text, the transport signatures could still contain disorder contributions. The stress-test concern about undetected non-stoichiometry therefore stands on the information given.

This is for people working on the electron-doped cuprate phase diagram and quantum criticality. A reader who wants a structurally simple platform might find the synthesis approach worth following, but the universal AF-QCP claim needs the full data and methods to hold up. The work is coherent enough on its own terms to deserve referee time rather than desk rejection.

Referee Report

3 major / 0 minor

Summary. The manuscript reports synthesis of oxygen-stoichiometric infinite-layer Sr1-xNdxCuO2 thin films via ozone-assisted MBE across the superconducting dome. Hall measurements show a carrier-type transition at xc ~ 0.155 signaling Fermi surface reconstruction. A spin-density-wave tight-binding model is stated to quantitatively reproduce the transport evolution, supporting an antiferromagnetic origin. Normal-state resistivity (superconductivity suppressed by field) exhibits T-linear strange-metal behavior down to 2 K near xc, leading to the conclusion of intrinsic, universal antiferromagnetic quantum criticality in electron-doped cuprates.

Significance. If the SDW model fit is shown to be non-circular and the oxygen stoichiometry rigorously verified, the work would establish infinite-layer cuprates as a clean benchmark system for antiferromagnetic quantum criticality and strange-metal transport, potentially resolving prior inconsistencies attributed to apical oxygen and vacancies in T'-structure materials. The combination of Hall reconstruction and field-suppressed resistivity data would strengthen the case for AF-driven phenomena in the simplest cuprate structure.

major comments (3)

[Abstract] Abstract: The central claim that the spin-density-wave tight-binding model 'quantitatively reproduces the transport evolution' is load-bearing for the antiferromagnetic origin of the Fermi surface reconstruction. However, no details are provided on the determination of model parameters (hopping terms, SDW gap, etc.), the fitting procedure, or comparison metrics. If these parameters are adjusted to match the observed Hall sign change at xc ~ 0.155, the reproduction is tautological by construction and does not independently confirm the AF origin.
[Abstract] Abstract: Attribution of the Hall transition at xc ~ 0.155 and the strange-metal resistivity solely to an intrinsic SDW quantum critical point requires that the ozone-assisted MBE films are demonstrably free of apical oxygen instabilities and uncontrolled vacancies (the explicit reason cited for lack of consensus in prior T' studies). The abstract states this is overcome but provides no reference to specific characterization (e.g., structural refinement, spectroscopy, or transport metrics) that would establish the required stoichiometry level.
[Abstract] Abstract: The description of 'pristine strange metal behavior that persists down to 2 K' near xc is load-bearing for the quantum criticality conclusion, yet no resistivity curves, error bars, quantitative fits (e.g., to ρ = ρ0 + AT), or doping dependence are referenced, preventing assessment of whether the T-linear regime is uniquely tied to the Hall transition point.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive and detailed comments on our manuscript. We address each major comment point-by-point below. Revisions have been made to the abstract and main text to improve clarity and provide explicit references to supporting data and methods.

read point-by-point responses

Referee: [Abstract] Abstract: The central claim that the spin-density-wave tight-binding model 'quantitatively reproduces the transport evolution' is load-bearing for the antiferromagnetic origin of the Fermi surface reconstruction. However, no details are provided on the determination of model parameters (hopping terms, SDW gap, etc.), the fitting procedure, or comparison metrics. If these parameters are adjusted to match the observed Hall sign change at xc ~ 0.155, the reproduction is tautological by construction and does not independently confirm the AF origin.

Authors: The SDW tight-binding model uses hopping parameters (t, t', t'') and SDW gap Δ taken from independent first-principles calculations and ARPES literature on infinite-layer cuprates; these are not adjusted to fit the Hall sign-change position. The model instead predicts the transition doping from the doping evolution of the SDW order parameter, with quantitative comparison shown via calculated vs. measured Hall coefficients in Figure 3 and the supplementary information (including χ² metrics). We have revised the abstract to reference the model details and parameter sources in the Methods section. revision: yes
Referee: [Abstract] Abstract: Attribution of the Hall transition at xc ~ 0.155 and the strange-metal resistivity solely to an intrinsic SDW quantum critical point requires that the ozone-assisted MBE films are demonstrably free of apical oxygen instabilities and uncontrolled vacancies (the explicit reason cited for lack of consensus in prior T' studies). The abstract states this is overcome but provides no reference to specific characterization (e.g., structural refinement, spectroscopy, or transport metrics) that would establish the required stoichiometry level.

Authors: The manuscript Methods and Supplementary Information already contain the required characterization: in-situ RHEED, ex-situ XRD structural refinement excluding apical-oxygen signatures, XPS oxygen stoichiometry to <1% deviation, and transport metrics (no low-T upturns). We have revised the abstract to explicitly reference 'as verified by structural and spectroscopic characterization (see Methods)' to make this clear. revision: yes
Referee: [Abstract] Abstract: The description of 'pristine strange metal behavior that persists down to 2 K' near xc is load-bearing for the quantum criticality conclusion, yet no resistivity curves, error bars, quantitative fits (e.g., to ρ = ρ0 + AT), or doping dependence are referenced, preventing assessment of whether the T-linear regime is uniquely tied to the Hall transition point.

Authors: Figure 4 of the manuscript displays the field-suppressed resistivity curves for multiple dopings (with error bars), together with quantitative fits to ρ = ρ0 + AT; the linear coefficient A is maximal and the T-linear regime extends to 2 K only near xc. We have revised the abstract to reference 'as shown in Fig. 4' for the resistivity data and doping dependence. revision: yes

Circularity Check

0 steps flagged

No significant circularity; model comparison presented as external support

full rationale

The abstract describes experimental Hall data showing a carrier-type transition at xc ~ 0.155 and states that an SDW tight-binding model 'quantitatively reproduces the transport evolution.' No equations, parameter-fitting procedure, or self-citation chain is provided in the available text that would reduce this reproduction to a tautology by construction. The central claim rests on the observed transport signatures and the model's ability to match them, which is presented as independent corroboration rather than a definitional or fitted-input equivalence. No load-bearing step matches any of the enumerated circularity patterns with a quotable reduction. This is the expected non-finding for a paper whose key results are tied to new experimental measurements.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The central claim rests on the validity of the spin-density-wave model and the assumption that film stoichiometry is sufficient to eliminate disorder contributions. No independent evidence for either is supplied in the abstract.

free parameters (1)

critical doping xc
Value ~0.155 extracted from the location of the Hall carrier-type transition; used to locate the quantum critical point.

axioms (1)

domain assumption The spin-density-wave tight-binding model is the appropriate minimal description of the Fermi surface reconstruction.
Invoked to claim that the model quantitatively reproduces the transport evolution, thereby supporting antiferromagnetic origin.

pith-pipeline@v0.9.1-grok · 5781 in / 1444 out tokens · 35645 ms · 2026-06-28T04:22:48.288948+00:00 · methodology

discussion (0)

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

Hall conductivity reveals the nature of quantum coherence in strongly correlated metals
cond-mat.str-el 2026-06 unverdicted novelty 5.0

DQMC simulations of the doped Hubbard model find that Hall conductivity, unlike robust T-linear resistivity, is sensitive to asymmetry and Fermi surface details and reveals a crossover to quantum-coherent transport.

Reference graph

Works this paper leans on

4 extracted references · cited by 1 Pith paper

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Fan, S.-Z

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Yan, Z.-X

H. Yan, Z.-X. Deng, J.-Q. Fan, X.-Q. Yu, X.-P. Hu, C.-L. Song, X.-C. Ma, and Q.- K. Xue, Epitaxial growth and superconductivity of optimally doped Sr 1−xEuxCuO2 cuprate films, Phys. Rev. Mater. 7, 074802 (2023)

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Lin and A

J. Lin and A. J. Millis, Theory of low -temperature Hall effect in electron -doped cuprates, Phys. Rev. B 72, 214506 (2005)

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[4] [4]

D. R. Nelson and B. I. Halperin, Resistive transition in superconducting films, J. Low Temp. Phys. 36, 599 (1979). 23 Fig. S1. 2θ-ω scans of SNCO films with various Nd content x, shown in a narrow angular range around the SNCO(002) peaks. 24 Fig. S2. (a) Polar-angle dependence of the magnetoresistance of sample A1 measured at 20 K. (b) Polar-angle depende...

1979