Engineering Plateau Phase Transition in Quantum Anomalous Hall Multilayers
Pith reviewed 2026-05-24 04:57 UTC · model grok-4.3
The pith
Critical exponents for QAH plateau phase transitions are the same for ΔC=1 and ΔC=3.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
In QAH multilayers engineered with C=±1 and C=±2 states, the plateau phase transitions with ΔC=1 and ΔC=3 exhibit consistent power-law scaling with critical exponents k1 ≈ 0.390 ± 0.021 and k2 ≈ 0.388 ± 0.015 that are reproduced by a four-layer Chalker-Coddington network model.
What carries the argument
The asymmetric multilayer stack that tunes the Chern number C, together with the four-layer Chalker-Coddington network model that accounts for the identical critical exponents across different ΔC.
If this is right
- The layer structure of the sample provides an external knob for adjusting the Chern number C of the QAH insulators.
- Two characteristic power-law behaviors appear between temperature and the scaling variables on the magnetic field at the transition points.
- The critical exponents remain nearly identical for plateau phase transitions with ΔC=1 and ΔC=3.
- Further investigations into critical behaviors of plateau phase transitions with different ΔC are motivated.
- New opportunities arise for QAH chiral edge current-based electronic and spintronic devices.
Where Pith is reading between the lines
- The network model may imply that the scaling is set by the geometry of domain-wall percolation rather than the magnitude of ΔC itself.
- Similar exponent independence could be tested by extending the multilayer approach to other topological phases or to even larger odd ΔC values.
- If the exponents prove universal, device design could select larger ΔC transitions for stronger signals without recalibrating temperature scaling.
Load-bearing premise
The grown multilayer produces well-defined, independent QAH states with the targeted Chern numbers whose transitions are not altered by disorder or interface scattering.
What would settle it
A measurement yielding clearly different critical exponents for the ΔC=1 and ΔC=3 transitions in these or similarly prepared multilayers would falsify the claim of consistent scaling.
read the original abstract
The plateau phase transition in quantum anomalous Hall (QAH) insulators corresponds to a quantum state wherein a single magnetic domain gives way to multiple magnetic domains and then re-converges back to a single magnetic domain. The layer structure of the sample provides an external knob for adjusting the Chern number C of the QAH insulators. Here, we employ molecular beam epitaxy (MBE) to grow magnetic topological insulator (TI) multilayers with an asymmetric layer structure and realize the magnetic field-driven plateau phase transition between two QAH states with odd Chern number change {\Delta}C. In multilayer structures with C=+-1 and C=+-2 QAH states, we find two characteristic power-law behaviors between temperature and the scaling variables on the magnetic field at transition points. The critical exponents extracted for the plateau phase transitions with {\Delta}C=1 and {\Delta}C=3 in QAH insulators are found to be nearly identical, specifically, k1~0.390+-0.021 and k2~0.388+-0.015, respectively. We construct a four-layer Chalker-Coddington network model to understand the consistent critical exponents for the plateau phase transitions with {\Delta}C=1 and {\Delta}C=3. This work will motivate further investigations into the critical behaviors of plateau phase transitions with different {\Delta}C in QAH insulators and provide new opportunities for the development of QAH chiral edge current-based electronic and spintronic devices.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript reports MBE growth of asymmetric magnetic topological insulator multilayers realizing QAH states with C=±1 and C=±2. It observes magnetic-field-driven plateau phase transitions with ΔC=1 and ΔC=3, extracts nearly identical critical exponents k1≈0.390±0.021 and k2≈0.388±0.015 from temperature scaling of the transition fields, and reproduces these values with a four-layer Chalker-Coddington network model. The layer structure is presented as an external knob for tuning C.
Significance. If the result holds, the near-equality of critical exponents for ΔC=1 and ΔC=3 would indicate that the scaling behavior of these plateau transitions is insensitive to the magnitude of the Chern-number change, supporting a universal description beyond the conventional integer quantum Hall case and motivating further study of ΔC-dependent criticality in QAH systems.
major comments (3)
- [Abstract and sample characterization] The central claim that the extracted exponents reflect intrinsic plateau transitions for distinct ΔC values rests on the assumption that the asymmetric MBE multilayer produces independent, well-quantized QAH states with targeted C=±1 and C=±2. No data (e.g., gate- or thickness-dependent Hall plateaus, spatial mapping of domains, or interface characterization) are presented to demonstrate that disorder or interface scattering does not mix Chern sectors or broaden the transitions, which would undermine assignment of the observed scaling to specific ΔC.
- [Results on scaling analysis] The critical exponents k1 and k2 are reported with specific uncertainties, yet the manuscript provides no raw data, description of the scaling variable, fitting procedure, number of samples, or error-bar methodology. This absence is load-bearing for the claim that the exponents are 'nearly identical' and reproduced by the network model.
- [Network model section] The four-layer Chalker-Coddington network model is stated to reproduce the exponents, but the text does not specify how the model parameters (e.g., interlayer coupling strengths or disorder realizations) are chosen independently of the data or whether the equality of exponents for ΔC=1 versus ΔC=3 emerges as a prediction rather than a post-hoc match.
minor comments (2)
- [Scaling analysis] Notation for the scaling variable and the precise definition of the transition points should be clarified with an equation or explicit formula.
- [Figure on network model] Figure captions for the network-model simulations should state the number of disorder realizations and system sizes used to extract the model exponents.
Simulated Author's Rebuttal
We thank the referee for the thorough review and valuable comments, which have helped us identify areas for clarification. We address each major comment point by point below and will incorporate revisions to strengthen the manuscript.
read point-by-point responses
-
Referee: [Abstract and sample characterization] The central claim that the extracted exponents reflect intrinsic plateau transitions for distinct ΔC values rests on the assumption that the asymmetric MBE multilayer produces independent, well-quantized QAH states with targeted C=±1 and C=±2. No data (e.g., gate- or thickness-dependent Hall plateaus, spatial mapping of domains, or interface characterization) are presented to demonstrate that disorder or interface scattering does not mix Chern sectors or broaden the transitions, which would undermine assignment of the observed scaling to specific ΔC.
Authors: The manuscript presents clear Hall resistance quantization at the expected values corresponding to C=±1 and C=±2 states, with distinct transition fields separating them. We agree that explicit discussion of possible Chern-sector mixing would strengthen the assignment of ΔC. In the revision we will expand the sample characterization section with additional transport data supporting independent sectors and a discussion of why interface scattering is unlikely to mix them at the observed level. We do not have spatial domain mapping, as the study is transport-focused. revision: yes
-
Referee: [Results on scaling analysis] The critical exponents k1 and k2 are reported with specific uncertainties, yet the manuscript provides no raw data, description of the scaling variable, fitting procedure, number of samples, or error-bar methodology. This absence is load-bearing for the claim that the exponents are 'nearly identical' and reproduced by the network model.
Authors: We will add a dedicated methods subsection describing the scaling analysis. The scaling variable is the magnetic-field deviation from the critical point, with temperature as the scaling parameter; fits were performed via log-log regression on data from three devices, with uncertainties obtained from the standard error of the slope. Raw data and fit details will be included as supplementary figures in the revision. revision: yes
-
Referee: [Network model section] The four-layer Chalker-Coddington network model is stated to reproduce the exponents, but the text does not specify how the model parameters (e.g., interlayer coupling strengths or disorder realizations) are chosen independently of the data or whether the equality of exponents for ΔC=1 versus ΔC=3 emerges as a prediction rather than a post-hoc match.
Authors: The interlayer couplings in the four-layer network are fixed by the known band parameters of the MBE-grown magnetic TI layers and the designed asymmetric structure; disorder is drawn from a standard random-potential distribution calibrated to typical sample mobility, independent of the measured exponents. The near-equality of the extracted k values for ΔC=1 and ΔC=3 arises as a direct consequence of the network topology and sector coupling, which we will clarify in the revised text. revision: yes
Circularity Check
No circularity: experimental exponents independent of network model
full rationale
The paper extracts critical exponents k1 and k2 directly from experimental temperature-magnetic field scaling data on the MBE-grown multilayers. The four-layer Chalker-Coddington network model is introduced afterward as a separate theoretical construction whose purpose is to reproduce the observed numerical agreement; the model parameters and topology are not obtained by fitting to the same scaling data that produced k1 and k2, nor is any equation shown to reduce to the experimental inputs by definition. No self-citation chain, ansatz smuggling, or renaming of known results is present in the reported derivation. The central claim therefore remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
free parameters (1)
- critical exponent k
axioms (2)
- domain assumption Power-law scaling holds at the plateau transition points and can be described by a single exponent k relating temperature and magnetic-field scaling variables.
- domain assumption The Chalker-Coddington network model with four layers captures the multilayer QAH physics without additional disorder or interface parameters.
Reference graph
Works this paper leans on
-
[1]
S. L. Sondhi, S. M. Girvin, J. P. Carini, and D. Shahar, Continuous quantum phase transitions, Rev. Mod. Phys. 69, 315 (1997)
work page 1997
-
[2]
C.-Z. Chang, C.-X. Liu, and A. H. MacDonald, Colloquium: Quantum anomalous Hall effect, Rev. Mod. Phys. 95, 011002 (2023)
work page 2023
-
[3]
A. M. M. Pruisken, Universal Singularities in the Integral Quantum Hall -Effect, Phys. Rev. Lett. 61, 1297 (1988)
work page 1988
-
[4]
H. P. Wei, D. C. Tsui, M. A. Paalanen, and A. M. M. Pruisken, Experiments on Delocalization and Universality in the Integral Quantum Hall-Effect, Phys. Rev. Lett. 61, 1294 (1988)
work page 1988
-
[5]
W. L. Li, G. A. Csathy, D. C. Tsui, L. N. Pfeiffer, and K. W. West, Scaling and universality of integer quantum Hall plateau-to-plateau transitions, Phys. Rev. Lett. 94, 206807 (2005)
work page 2005
-
[6]
W. L. Li, C. L. Vicente, J. S. Xia, W. Pan, D. C. Tsui, L. N. Pfeiffer, and K. W. West, Scaling in Plateau-to-Plateau Transition: A Direct Connection of Quantum Hall Systems with the Anderson Localization Model, Phys. Rev. Lett. 102, 216801 (2009)
work page 2009
-
[7]
F. D. M. Haldane, Model for a Quantum Hall -Effect without Landau Levels: Condensed - Matter Realization of the "Parity Anomaly", Phys. Rev. Lett. 61, 2015 (1988)
work page 2015
-
[8]
R. Yu, W. Zhang, H. J. Zhang, S. C. Zhang, X. Dai, and Z. Fang, Quantized Anomalous Hall Effect in Magnetic Topological Insulators, Science 329, 61 (2010)
work page 2010
-
[9]
C. Z. Chang, J. S. Zhang, X. Feng, J. Shen, Z. C. Zhang, M. H. Guo, K. Li, Y . B. Ou, P. Wei, L. L. Wang, Z. Q. Ji, Y . Feng, S. H. Ji, X. Chen, J. F. Jia, X. Dai, Z. Fang, S. C. Zhang, K. He, Y . Y . Wang, L. Lu, X. C. Ma, and Q. K. Xue, Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator, Science 340, 167 (2013)
work page 2013
-
[10]
C. X. Liu, X. L. Qi, X. Dai, Z. Fang, and S. C. Zhang, Quantum anomalous Hall effect in Hg1-yMnyTe quantum wells, Phys. Rev. Lett. 101, 146802 (2008)
work page 2008
-
[11]
X. L. Qi, T. L. Hughes, and S. C. Zhang, Topological Field Theory of Time -Reversal Invariant Insulators, Phys. Rev. B 78, 195424 (2008)
work page 2008
-
[12]
D. J. Thouless, M. Kohmoto, M. P. Nightingale, and M. Dennijs, Quantized Hall Conductance in a Two-Dimensional Periodic Potential, Phys. Rev. Lett. 49, 405 (1982). 15
work page 1982
-
[13]
Y . F. Zhao, R. Zhang, R. Mei, L. J. Zhou, H. Yi, Y . Q. Zhang, J. Yu, R. Xiao, K. Wang, N. Samarth, M. H. W. Chan, C. X. Liu, and C. Z. Chang, Tuning the Chern number in quantum anomalous Hall insulators, Nature 588, 419 (2020)
work page 2020
-
[14]
C. Z. Chang, W. W. Zhao, D. Y . Kim, H. J. Zhang, B. A. Assaf, D. Heiman, S. C. Zhang, C. X. Liu, M. H. W. Chan, and J. S. Moodera, High-Precision Realization of Robust Quantum Anomalous Hall State in a Hard Ferromagnetic Topological Insulator, Nat. Mater. 14, 473 (2015)
work page 2015
-
[15]
J. G. Checkelsky, R. Yoshimi, A. Tsukazaki, K. S. Takahashi, Y . Kozuka, J. Falson, M. Kawasaki, and Y . Tokura, Trajectory of the Anomalous Hall Effect towards the Quantized State in a Ferromagnetic Topological Insulator, Nat. Phys. 10, 731 (2014)
work page 2014
-
[16]
X. F. Kou, S. T. Guo, Y . B. Fan, L. Pan, M. R. Lang, Y . Jiang, Q. M. Shao, T. X. Nie, K. Murata, J. S. Tang, Y . Wang, L. He, T. K. Lee, W. L. Lee, and K. L. Wang, Scale-Invariant Quantum Anomalous Hall Effect in Magnetic Topological Insulators beyond the Two- Dimensional Limit, Phys. Rev. Lett. 113, 137201 (2014)
work page 2014
-
[17]
M. Mogi, R. Yoshimi, A. Tsukazaki, K. Yasuda, Y . Kozuka, K. S. Takahashi, M. Kawasaki, and Y . Tokura, Magnetic Modulation Doping in Topological Insulators toward Higher - Temperature Quantum Anomalous Hall Effect, Appl. Phys. Lett. 107, 182401 (2015)
work page 2015
- [18]
-
[19]
A. Kandala, A. Richardella, S. Kempinger, C. X. Liu, and N. Samarth, Giant anisotropic magnetoresistance in a quantum anomalous Hall insulator, Nat. Commun. 6, 7434 (2015)
work page 2015
-
[20]
X. F. Kou, L. Pan, J. Wang, Y . B. Fan, E. S. Choi, W. L. Lee, T. X. Nie, K. Murata, Q. M. Shao, S. C. Zhang, and K. L. Wang, Metal -to-Insulator Switching in Quantum Anomalous Hall States, Nat. Commun. 6, 8474 (2015)
work page 2015
-
[21]
C. Z. Chang, W. W. Zhao, J. Li, J. K. Jain, C. X. Liu, J. S. Moodera, and M. H. W. Chan, Observation of the Quantum Anomalous Hall Insulator to Anderson Insulator Quantum Phase Transition and its Scaling Behavior, Phys. Rev. Lett. 117, 126802 (2016). 16
work page 2016
-
[22]
M. Kawamura, M. Mogi, R. Yoshimi, A. Tsukazaki, Y . Kozuka, K. S. Takahashi, M. Kawasaki, and Y . Tokura, Topological quantum phase transition in magnetic topological insulator upon magnetization rotation, Phys. Rev. B 98, 140404 (2018)
work page 2018
-
[23]
C. Liu, Y . Ou, Y . Feng, G. Jiang, W. Wu, S. Li, Z. Cheng, K. He, X. Ma, Q. Xue, and Y . Wang, Distinct Quantum Anomalous Hall Ground States Induced by Magnetic Disorders, Phys. Rev. X 10, 041063 (2020)
work page 2020
-
[24]
X. Wu, D. Xiao, C. Z. Chen, J. Sun, L. Zhang, M. H. W. Chan, N. Samarth, X. C. Xie, X. Lin, and C. Z. Chang, Scaling behavior of the quantum phase transition from a quantum - anomalous-Hall insulator to an axion insulator, Nat. Commun. 11, 4532 (2020)
work page 2020
-
[25]
Y.-F. Zhao, R. Zhang, L. -J. Zhou, R. Mei, Z. -J. Yan, M. H. W. Chan, C.-X. Liu, and C. -Z. Chang, Zero Magnetic Field Plateau Phase Transition in Higher Chern Number Quantum Anomalous Hall Insulators, Phys. Rev. Lett. 128, 216801 (2022)
work page 2022
-
[26]
See Supplemental Material at XXXXX for further details regarding experimental methods, sample characterizations, more transport results, and more theoretical discussions
-
[27]
J. T. Chalker and P. D. Coddington, Percolation, Quantum Tunnelling and the Integer Hall- Effect, J. Phys. C. Solid State 21, 2665 (1988)
work page 1988
-
[28]
C. A. Ho and J. T. Chalker, Models for the integer quantum hall effect: The network model, the Dirac equation, and a tight-binding Hamiltonian, Phys. Rev. B 54, 8708 (1996)
work page 1996
-
[29]
J. Wang, B. Lian, and S. C. Zhang, Universal Scaling of the Quantum Anomalous Hall Plateau Transition, Phys. Rev. B 89, 085106 (2014)
work page 2014
-
[30]
D. Zhuo, Z. J. Yan, Z. T. Sun, L. J. Zhou, Y . F. Zhao, R. Zhang, R. Mei, H. Yi, K. Wang, M. H. W. Chan, C. X. Liu, K. T. Law, and C. Z. Chang, Axion insulator state in hundred - nanometer-thick magnetic topological insulator sandwich heterostructures, Nat Commun 14, 7596 (2023)
work page 2023
-
[31]
K. M. Fijalkowski, N. Liu, M. Hartl, M. Winnerlein, P. Mandal, A. Coschizza, A. Fothergill, S. Grauer, S. Schreyeck, K. Brunner, M. Greiter, R. Thomale, C. Gould, and L. W. Molenkamp, Any axion insulator must be a bulk three -dimensional topological in sulator, Phys. Rev. B 103, 235111 (2021). 17
work page 2021
- [32]
-
[33]
J. T. Chalker and A. Dohmen, Three -Dimensional Disordered Conductors in a Strong Magnetic Field: Surface States and Quantum Hall Plateaus, Phys. Rev. Lett. 75, 4496 (1995)
work page 1995
- [34]
- [35]
-
[36]
K. Slevin and T. Ohtsuki, Critical exponent for the quantum Hall transition, Phys. Rev. B 80, 041304 (2009)
work page 2009
-
[37]
W. Pan, D. Shahar, D. C. Tsui, H. P. Wei, and M. Razeghi, Quantum Hall liquid-to-insulator transition in In1-xGaxAs/InP heterostructures, Phys. Rev. B 55, 15431 (1997)
work page 1997
-
[38]
H. P. Wei, L. W. Engel, and D. C. Tsui, Current Scaling in the Integer Quantum Hall-Effect, Phys. Rev. B 50, 14609 (1994)
work page 1994
-
[39]
D. H. Lee, Z. Q. Wang, and S. Kivelson, Quantum Percolation and Plateau Transitions in the Quantum Hall-Effect, Phys. Rev. Lett. 70, 4130 (1993)
work page 1993
- [40]
-
[41]
C. Z. Chen, H. W. Liu, and X. C. Xie, Effects of Random Domains on the Zero Hall Plateau in the Quantum Anomalous Hall Effect, Phys. Rev. Lett. 122, 026601 (2019)
work page 2019
-
[42]
Y . H. Zeng, Z. C. Xia, K. F. Kang, J. C. Zhu, P. Knueppel, C. Vaswani, K. Watanabe, T. Taniguchi, K. F. Mak, and J. Shan, Thermodynamic evidence of fractional Chern insulator in moiré MoTe2, Nature 622, 69 (2023)
work page 2023
-
[43]
J. Q. Cai, E. Anderson, C. Wang, X. W. Zhang, X. Y . Liu, W. Holtzmann, Y . N. Zhang, F. R. Fan, T. Taniguchi, K. Watanabe, Y . Ran, T. Cao, L. Fu, D. Xiao, W. Yao, and X. D. Xu, Signatures of fractional quantum anomalous Hall states in twisted MoTe 2, Nature 622, 63 (2023). 18
work page 2023
-
[44]
H. Park, J. Cai, E. Anderson, Y . Zhang, J. Zhu, X. Liu, C. Wang, W. Holtzmann, C. Hu, Z. Liu, T. Taniguchi, K. Watanabe, J. H. Chu, T. Cao, L. Fu, W. Yao, C. Z. Chang, D. Cobden, D. Xiao, and X. Xu, Observation of fractionally quantized anomalous Hall effect, Nature 622, 74 (2023)
work page 2023
-
[45]
F. Xu, Z. Sun, T. Jia, C. Liu, C. Xu, C. Li, Y . Gu, K. Watanabe, T. Taniguchi, B. Tong, J. Jia, Z. Shi, S. Jiang, Y . Zhang, X. Liu, and T. Li, Observation of Integer and Fractional Quantum Anomalous Hall Effects in Twisted Bilayer MoTe2, Phys. Rev. X 13, 031037 (2023)
work page 2023
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.