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arxiv: 1907.00898 · v2 · pith:NYS4O6GBnew · submitted 2019-07-01 · ❄️ cond-mat.mes-hall · cond-mat.mtrl-sci

Stable structures and electronic properties of perovskite oxide monolayers

Xiang-Bo Xiao , Bang-Gui Liu This is my paper

Pith reviewed 2026-05-25 11:27 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall cond-mat.mtrl-sci
keywords perovskite oxide monolayers2D materialsfirst-principles calculationswide-gap semiconductorsferromagnetic metalout-of-plane dipoleSrTiO3LaAlO3
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The pith

Four perovskite oxide monolayers from SrTiO3, LaAlO3, KTaO3 and BaFeO3 are stable as 2D sheets, three as wide-gap semiconductors and one as a ferromagnetic metal.

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

The paper uses first-principles calculations to relax tetragonal perovskite structures into 2D monolayers and checks their stability. It reports that dangling bonds are overcome in the first three cases to produce wide-gap semiconductors, while the BaFeO3-derived monolayer remains metallic and carries isotropic Heisenberg ferromagnetism. Each monolayer shows a sizable electrostatic potential difference between its two faces, which corresponds to a large out-of-plane dipole. These features are presented as a new family of 2D materials that could be incorporated into devices that already exploit perovskite heterostructures.

Core claim

Four stable 2D monolayer materials are identified from SrTiO3, LaAlO3, KTaO3, and BaFeO3. The first three monolayers become wide-gap semiconductors once dangling bonds are overcome, while the BaFeO3 monolayer is a 2D isotropic Heisenberg ferromagnetic metal. A large electrostatic potential energy difference exists between the two sides of each monolayer, reflecting a large out-of-plane dipole.

What carries the argument

First-principles structural relaxation and electronic-structure calculation of tetragonal perovskite oxide monolayers, with emphasis on stability after removal of dangling bonds.

If this is right

  • The three semiconductor monolayers supply 2D wide-gap building blocks for oxide-based electronics.
  • The BaFeO3 monolayer supplies a 2D ferromagnetic metal whose isotropic Heisenberg character can be tested in low-dimensional spin models.
  • The large out-of-plane dipoles in all four monolayers create built-in electric fields usable for electrostatic gating or piezoelectric response.
  • The monolayers can be stacked with existing perovskite heterostructures to produce new interface phenomena.

Where Pith is reading between the lines

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

  • If the monolayers can be transferred or grown on substrates, their dipoles may allow electrostatic control of carrier density without external gates.
  • The same computational route could be applied to other perovskite compositions to enlarge the set of predicted 2D oxide sheets.
  • The combination of out-of-plane dipole and in-plane isotropy in the ferromagnetic case suggests possible use in 2D spintronic devices where magnetization direction is decoupled from lattice orientation.

Load-bearing premise

The calculations correctly predict both the structural stability and the electronic character of the monolayers without further experimental checks or functional adjustments.

What would settle it

Experimental growth of any of the four monolayers followed by direct measurement of band gap, magnetic order, or surface potential difference that contradicts the computed values.

Figures

Figures reproduced from arXiv: 1907.00898 by Bang-Gui Liu, Xiang-Bo Xiao.

Figure 2
Figure 2. Figure 2: FIG. 2. (Color online) The phonon dispersion spectra of the [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 1
Figure 1. Figure 1: FIG. 1. (Color online) The intrinsic average electrostatic [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (Color online) The band structures of the four mono [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. (Color online) The total and atom-orbital-resolved [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
read the original abstract

It is highly desirable to search for promising two-dimensional (2D) monolayer materials for deep insight of 2D materials and applications. We use first-principles method to investigate tetragonal perovskite oxide monolayers as 2D materials. We find four stable 2D monolayer materials from SrTiO$_3$, LaAlO$_3$, KTaO$_3$, and BaFeO$_3$, denoting them as STO-ML, LAO-ML, KTO-ML, and BFO-ML. Our further study shows that through overcoming dangling bonds the first three monolayers are 2D wide-gap semiconducotors, and BFO-ML is a 2D isotropic Heisenberg ferromagnetic metal. There is a large electrostatic potential energy difference between the two sides, reflecting a large out-of-plane dipole, in each of the monolayers. These make a series of 2D monolayer materials, and should be useful in novel electronic devices considering emerging phenomena in perovskite oxide heterostructures.

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 first-principles investigations of tetragonal perovskite oxide monolayers derived from SrTiO₃ (STO-ML), LaAlO₃ (LAO-ML), KTaO₃ (KTO-ML), and BaFeO₃ (BFO-ML). The authors claim to have identified four stable 2D structures, with STO-ML, LAO-ML, and KTO-ML being wide-gap semiconductors and BFO-ML an isotropic Heisenberg ferromagnetic metal, each possessing a large out-of-plane dipole moment as evidenced by electrostatic potential differences across the monolayer.

Significance. Should the computational predictions prove robust upon provision of full methodological details and verification, this work would contribute to the field by proposing new 2D monolayer materials based on common perovskites. These could enable studies of 2D wide-gap semiconductors and ferromagnetic metals with intrinsic dipoles, potentially relevant for heterostructure-inspired devices. The approach of overcoming dangling bonds to achieve these properties is of interest if substantiated.

major comments (2)
  1. [Computational methods] Computational methods section: The manuscript provides no details on the exchange-correlation functional employed, the plane-wave energy cutoff, k-point grid density, vacuum spacing in the supercell, or convergence criteria. For oxide monolayers, these choices are critical in determining whether the structures are dynamically stable and in accurately predicting band gaps and magnetic ordering, as standard GGA functionals can underestimate gaps and influence magnetic states.
  2. [Stability analysis] Stability analysis (abstract and results): The claim that the four monolayers are 'stable' is not supported by any reported evidence such as phonon dispersion calculations to confirm the absence of imaginary frequencies or comparisons of formation energies. Without this, the central assertion of stable 2D materials cannot be evaluated.
minor comments (2)
  1. [Abstract] Typo: 'semiconducotors' should be 'semiconductors'.
  2. [Abstract] The description of BFO-ML as a '2D isotropic Heisenberg ferromagnetic metal' would benefit from clarification on whether this refers to a specific model Hamiltonian or just the DFT-predicted ferromagnetic metallic state.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful review and constructive comments on our manuscript. We address the major comments point by point below.

read point-by-point responses

  1. Referee: [Computational methods] Computational methods section: The manuscript provides no details on the exchange-correlation functional employed, the plane-wave energy cutoff, k-point grid density, vacuum spacing in the supercell, or convergence criteria. For oxide monolayers, these choices are critical in determining whether the structures are dynamically stable and in accurately predicting band gaps and magnetic ordering, as standard GGA functionals can underestimate gaps and influence magnetic states.

    Authors: We agree that the original submission omitted these methodological details, which are essential for reproducibility and evaluation. In the revised manuscript we will add a complete Computational Methods section specifying the exchange-correlation functional, plane-wave cutoff, k-point sampling, vacuum spacing, and convergence criteria used. revision: yes

  2. Referee: [Stability analysis] Stability analysis (abstract and results): The claim that the four monolayers are 'stable' is not supported by any reported evidence such as phonon dispersion calculations to confirm the absence of imaginary frequencies or comparisons of formation energies. Without this, the central assertion of stable 2D materials cannot be evaluated.

    Authors: The referee correctly notes that no phonon dispersions or formation-energy comparisons were provided to substantiate the stability claims. We will include phonon dispersion calculations demonstrating the absence of imaginary frequencies for all four monolayers, together with formation-energy data, in the revised manuscript. revision: yes

Circularity Check

0 steps flagged

No circularity: results are direct outputs of first-principles calculations

full rationale

The paper reports outcomes from standard first-principles DFT relaxations and electronic-structure computations on tetragonal perovskite monolayers (STO-ML, LAO-ML, KTO-ML, BFO-ML). Stability, wide-gap semiconducting character, ferromagnetic metallicity, and out-of-plane dipoles are presented as computational results, not as quantities derived by definition, fitted parameters renamed as predictions, or load-bearing self-citations. No equations, ansatzes, or uniqueness theorems in the provided text reduce any claim to its own inputs. The derivation chain is self-contained against external benchmarks (DFT codes and functionals), warranting a zero circularity score.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

Review based on abstract only; computational parameters and full derivation details unavailable.

free parameters (1)
  • DFT exchange-correlation functional and numerical parameters
    Standard but unspecified choices in first-principles calculations that affect predicted stability and band gaps.
axioms (1)
  • domain assumption Tetragonal perovskite structures can form stable 2D monolayers once dangling bonds are overcome.
    Invoked in the abstract to explain the reported stability of the four monolayers.

pith-pipeline@v0.9.0 · 5702 in / 1246 out tokens · 23721 ms · 2026-05-25T11:27:17.998726+00:00 · methodology

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Reference graph

Works this paper leans on

24 extracted references · 24 canonical work pages

  1. [1]

    K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. 5 Firsov, Electric Field Effect in Atomically Thin Carbon Films. Science 306, 666-669 (2004)

    work page 2004

  2. [2]

    A. K. Geim and K. S. Novoselov, The Rising of Graphene. Nat. Mater. 6, 183-191 (2007)

    work page 2007

  3. [3]

    Yankowitz et al., Emergence of superlattice Dirac points in graphene on hexagonal boron nitride

    M. Yankowitz et al., Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nat. Phys. 8, 382-386 (2012)

    work page 2012

  4. [4]

    K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, Atomically thin MoS2: A new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010)

    work page 2010

  5. [5]

    K. S. Novoselov, A. Mishchenko, A. Carvalho, and A. H. Castro Neto, 2D materials and van der Waals het- erostructures, Science 353, 461 (2016)

    work page 2016

  6. [6]

    Tan, X.-H

    C.-L. Tan, X.-H. Cao, X.-J. Wu, Q.-Y. He, J. Yang, X. Zhang, J.-C. Chen, W. Zhao, S.-K. Han, G.-H. Nam, M. Sindoro, and H. Zhang, Recent Advances in Ultrathin Two-Dimensional Nanomaterials, Chemical Reviews 117, 6225-6331 (2017)

    work page 2017

  7. [7]

    Zhang, Y.-W

    Y. Zhang, Y.-W. Tan, H. L. Stormer, P. Kim, Experimen- tal Observation of the Quantum Hall Effect and Berrys Phase in Graphene, Nature 438, 201-204 (2005)

    work page 2005

  8. [8]

    Xiao, G.-B

    D. Xiao, G.-B. Liu, W. Feng, X. Xu, W. Yao, Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 108, 196802 (2012)

    work page 2012

  9. [9]

    Ren, Z.-H

    Y.-F. Ren, Z.-H. Qiao, and Q. Niu, Topological phases in two-dimensional materials: a review, Rep. Prog. Phys. 79, 066501 (2016)

    work page 2016

  10. [10]

    M. C. Lucking, W. Xie, D.-H. Choe, D. West, T.-M. Lu, and S. B. Zhang, Traditional Semiconductors in the Two- Dimensional Limit, Phys. Rev. Lett. 120, 086101 (2018)

    work page 2018

  11. [11]

    Ohtomo and H

    A. Ohtomo and H. Y. Hwang, A high-mobility electron gas at the LaAlO 3/SrTiO3 heterointerface. Nature 427, 423-426 (2004)

    work page 2004

  12. [12]

    H. Lee, N. Campbell, J. Lee, T. J. Asel, T. R. Paudel, H. Zhou, J. W. Lee, B. Noesges, J. Seo, B. Park, L. J. Brillson, S. H. Oh, E. Y. Tsymbal, M. S. Rzchowski, and C. B. Eom, Direct observation of a two-dimensional hole gas at oxide interfaces, Nat. Mater. 17, 231 (2018)

    work page 2018

  13. [13]

    Brinkman et al

    A. Brinkman et al. Magnetic effects at the interface between non-magnetic oxides, Nat. Mater. 6, 493-496 (2007)

    work page 2007

  14. [14]

    Reyren et al

    N. Reyren et al. Superconducting interfaces between in - sulating oxides, Science 317, 1196-1199 (2007)

    work page 2007

  15. [15]

    A. D. Caviglia et al. Electric field control of the LaAlO3/SrTiO3 interface ground state, Nature 456, 624- 627 (2008)

    work page 2008

  16. [16]

    Ji, S.-H

    D.-X. Ji, S.-H. Cai, T. R. Paudel, H.-Y. Sun, C.-C. Zhang, L. Han, Y.-F. Wei, Y.-P. Zang, M. Gu, Y. Zhang, W.-P. Gao, H.-X. Huyan, W. Guo, D. Wu, Z.-B. Gu, E. Y. Tsymbal, P. Wang, Y.-F. Nie, and X.-Q. Pan, Free- standing crystalline oxide perovskites down to the mono- layer limit, Nature 570, 87 (2019)

    work page 2019

  17. [17]

    P. E. Blochl, Phys. Rev. B. 50, 17953 (1994)

    work page 1994

  18. [18]

    Hohenberg and W

    P. Hohenberg and W. Kohn, Phys. Rev. 136, B864 (1964)

    work page 1964

  19. [19]

    Kohn and L

    W. Kohn and L. J. Sham, Phys. Rev. 140, A1133 (1965)

    work page 1965

  20. [20]

    Kresse and J

    G. Kresse and J. Hafner, Phys. Rev. B 47, 558 (1993)

    work page 1993

  21. [21]

    Kresse and J

    G. Kresse and J. Furthmuller, Phys. Rev. B 54, 11169 (1996)

    work page 1996

  22. [22]

    J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996)

    work page 1996

  23. [23]

    Franchini, T

    C. Franchini, T. Archer, J. He, X. Q. Chen, A. Filippetti and S. Sanvito, Phys. Rev. B 83, 220402 (2011)

    work page 2011

  24. [24]

    A. Togo, I. Tanaka, and F. Oba, Phys. Rev. B 78, 134106 (2008)

    work page 2008