Incipient magnetic instability in RuO₂ with random phase approximation
Pith reviewed 2026-05-14 21:44 UTC · model grok-4.3
The pith
In stoichiometric RuO2 without spin-orbit coupling, commensurate altermagnetic order is the leading magnetic instability at low temperatures.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Using Hartree-Fock followed by random phase approximation on a three-orbital Hubbard model without spin-orbit coupling, the analysis of static susceptibility eigenvalues shows spin susceptibility dominates. In the stoichiometric system, commensurate altermagnetic order is the leading instability at low temperatures, while incommensurate vectors emerge at higher temperatures or with hole doping. The staggered Weiss field splits bands differently in altermagnets than in antiferromagnets.
What carries the argument
Eigenvalues and eigenvectors of the static susceptibility matrix from the random phase approximation, identifying the dominant magnetic instability channel and wave vector.
If this is right
- Commensurate altermagnetism is the ground state instability in undoped RuO2 at low T.
- Incommensurate magnetic orders are preferred at elevated temperatures or upon hole doping.
- The spin channel is the primary response over charge and other channels.
- Qualitative differences in band splitting distinguish altermagnetic from antiferromagnetic order.
Where Pith is reading between the lines
- Experiments on pure RuO2 at very low temperatures could confirm or refute the predicted commensurate order.
- Similar modeling approaches may apply to other proposed altermagnets to predict their ordering temperatures.
- Tuning via doping or temperature could be used to switch between magnetic phases in RuO2 devices.
- Including spin-orbit coupling, omitted here, might stabilize different instabilities or suppress the altermagnetic one.
Load-bearing premise
The three-orbital Hubbard model without spin-orbit coupling combined with Hartree-Fock and RPA accurately describes the magnetic response of real RuO2.
What would settle it
If neutron scattering or other probes find no magnetic order or an incommensurate order in stoichiometric RuO2 at low temperatures, the prediction of commensurate altermagnetism as the leading instability would be falsified.
Figures
read the original abstract
We study the instability in RuO$_2$ using the Hartree-Fock approximation followed by the random phase approximation. We employ a three-orbital Hubbard model without spin-orbit coupling. An analysis of the eigenvalues and eigenvectors of the static susceptibility in the non-magnetic phase for various local interaction parameters $U$, $J_H$, and hole doping $n$ shows that the spin susceptibility is the dominant response channel. In the stoichiometric system without spin-orbit coupling, commensurate altermagnetic order is identified as the leading instability at sufficiently low temperatures, whereas at higher temperatures or finite hole doping, incommensurate wave vectors emerge. To elucidate the origin of the magnetic instability, we analyze the band spitting by the staggered Weiss field and discuss the qualitative difference between altermagnets and antiferromagnets.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript studies magnetic instabilities in RuO2 via a three-orbital Hubbard model (no SOC) treated in Hartree-Fock followed by RPA. Analysis of eigenvalues and eigenvectors of the static susceptibility in the non-magnetic phase, for varying U, JH and hole doping n, shows spin susceptibility dominates; in the stoichiometric limit the leading instability at low T is identified as commensurate altermagnetic order, while incommensurate vectors appear at higher T or finite doping. Band splitting under a staggered Weiss field is used to contrast altermagnets with conventional antiferromagnets.
Significance. If the model faithfully represents the dominant response, the work supplies a concrete microscopic route to altermagnetic order in RuO2 and clarifies how the staggered Weiss field splits bands differently from antiferromagnets. The RPA eigenvalue analysis offers a systematic, parameter-dependent way to rank competing instabilities, which is useful for materials where altermagnetism is conjectured but not yet confirmed by direct experiment.
major comments (3)
- [Abstract and Results] The central identification of commensurate altermagnetic order as the leading instability (abstract and results) rests on the largest eigenvalue of the RPA susceptibility matrix occurring at the commensurate wavevector and diverging first upon lowering T. No numerical values are supplied for the critical U/JH ratio, the temperature scale, or the magnitude of the eigenvalue divergence, nor are convergence checks with respect to k-mesh density or interaction cutoff reported; without these the claim that the instability is 'at sufficiently low temperatures' remains qualitative and difficult to assess for robustness.
- [Model Hamiltonian] The three-orbital Hubbard model without SOC is adopted as the starting point (model section). Because real RuO2 possesses non-negligible spin-orbit coupling that can shift nesting vectors and mix orbital characters, the paper should demonstrate that the altermagnetic peak remains the largest eigenvalue when a small SOC term is added or when the tight-binding parameters are taken from a full DFT downfolding that includes all t2g and eg states; otherwise the reported leading instability risks being an artifact of the orbital truncation and SOC omission.
- [Discussion] The distinction between altermagnets and antiferromagnets is drawn from the band splitting induced by the staggered Weiss field (discussion). A quantitative plot or table comparing the RPA susceptibility intensity at the commensurate altermagnetic vector versus nearby incommensurate vectors, for the same set of U, JH and n values, would be required to substantiate that the altermagnetic channel is unambiguously dominant rather than merely competitive.
minor comments (2)
- The manuscript would benefit from explicit statements of the numerical values of U and JH (in eV) used for the stoichiometric plots and from a brief description of the k-point sampling employed in the susceptibility calculations.
- Figure captions should specify the temperature or interaction parameters at which each susceptibility map is evaluated so that readers can directly connect the panels to the claims about low-T versus high-T behavior.
Simulated Author's Rebuttal
We thank the referee for the careful reading and constructive comments on our manuscript. We address each major comment below and indicate the revisions we will make.
read point-by-point responses
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Referee: [Abstract and Results] The central identification of commensurate altermagnetic order as the leading instability (abstract and results) rests on the largest eigenvalue of the RPA susceptibility matrix occurring at the commensurate wavevector and diverging first upon lowering T. No numerical values are supplied for the critical U/JH ratio, the temperature scale, or the magnitude of the eigenvalue divergence, nor are convergence checks with respect to k-mesh density or interaction cutoff reported; without these the claim that the instability is 'at sufficiently low temperatures' remains qualitative and difficult to assess for robustness.
Authors: We agree that quantitative details would make the identification more robust. In the revised manuscript we will report the critical U/JH values at which the leading eigenvalue diverges, provide an estimate of the temperature scale from the T-dependence of the susceptibility, and include convergence tests with respect to k-mesh density. revision: yes
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Referee: [Model Hamiltonian] The three-orbital Hubbard model without SOC is adopted as the starting point (model section). Because real RuO2 possesses non-negligible spin-orbit coupling that can shift nesting vectors and mix orbital characters, the paper should demonstrate that the altermagnetic peak remains the largest eigenvalue when a small SOC term is added or when the tight-binding parameters are taken from a full DFT downfolding that includes all t2g and eg states; otherwise the reported leading instability risks being an artifact of the orbital truncation and SOC omission.
Authors: The three-orbital model without SOC is chosen to isolate the correlation-driven altermagnetic instability within the t2g manifold. We will add a symmetry-based discussion showing that a small SOC term is not expected to alter the leading character of the instability. A full numerical demonstration with SOC or a complete DFT downfolding lies outside the present scope. revision: partial
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Referee: [Discussion] The distinction between altermagnets and antiferromagnets is drawn from the band splitting induced by the staggered Weiss field (discussion). A quantitative plot or table comparing the RPA susceptibility intensity at the commensurate altermagnetic vector versus nearby incommensurate vectors, for the same set of U, JH and n values, would be required to substantiate that the altermagnetic channel is unambiguously dominant rather than merely competitive.
Authors: We agree that an explicit comparison is useful. The revised manuscript will include a new figure (or table) that directly compares the largest susceptibility eigenvalues at the commensurate altermagnetic vector with those at nearby incommensurate vectors for representative values of U, JH and n. revision: yes
- A complete numerical verification of the leading instability after inclusion of SOC or using a full DFT downfolding that incorporates all t2g and eg states.
Circularity Check
No significant circularity; susceptibility eigenvalues computed directly from model
full rationale
The paper constructs a three-orbital Hubbard Hamiltonian, solves it in the non-magnetic Hartree-Fock approximation, and then evaluates the static spin susceptibility matrix via RPA. The leading instability is identified by inspecting the largest eigenvalue and its wavevector for given U, JH, and filling; this identification is a direct numerical output of the chosen model parameters and does not reduce to a fit, a self-citation, or a definitional tautology. No load-bearing step relies on prior results by the same authors or on an ansatz smuggled through citation. The derivation chain is therefore self-contained within the stated model and approximation.
Axiom & Free-Parameter Ledger
free parameters (3)
- U
- JH
- n
axioms (3)
- domain assumption Three-orbital Hubbard model without spin-orbit coupling
- standard math Hartree-Fock approximation for the non-magnetic phase
- standard math Random phase approximation for static susceptibility
Reference graph
Works this paper leans on
-
[1]
and the magnon spectra, we employ the RPA approx- imation on the real-frequency axis, ˆχ(q, ω) = ˆχ0(q, ω) h 1+ ˆUˆχ0(q, ω) i−1 .(3) Here, ˆUdenotes the interaction matrix that has, as well as other quantities in Eq (3), size 72×72. The bubbleχ 0 on the imaginary-frequency axis is given by the product of one-particle Green’s functions Gℓσs,nσs ′(k, iν) = ...
-
[2]
A. N. Guthrie and L. T. Bourland, Magnetic susceptibil- ities and ionic moments in the palladium and platinum groups, Phys. Rev.37, 303 (1931)
work page 1931
-
[3]
W. D. Ryden and A. W. Lawson, Magnetic susceptibility of iro2 and ruo2, The Journal of Chemical Physics52, 6058 (1970)
work page 1970
-
[4]
E. Cordfunke, R. Konings, E. Westrum, and R. Shaviv, The thermophysical and thermochemical properties of ruo2 from 0 to 1000 k, Journal of Physics and Chemistry of Solids50, 429 (1989)
work page 1989
-
[5]
J. J. Lin, S. M. Huang, Y. H. Lin, T. C. Lee, H. Liu, X. X. Zhang, R. S. Chen, and Y. S. Huang, Low tem- perature electrical transport properties of ruo2 and iro2 single crystals, Journal of Physics: Condensed Matter 16, 8035 (2004)
work page 2004
-
[6]
T. Berlijn, P. C. Snijders, O. Delaire, H.-D. Zhou, T. A. Maier, H.-B. Cao, S.-X. Chi, M. Matsuda, Y. Wang, M. R. Koehler, P. R. C. Kent, and H. H. Weitering, Itin- erant antiferromagnetism in ruo 2, Phys. Rev. Lett.118, 077201 (2017)
work page 2017
-
[7]
Z. H. Zhu, J. Strempfer, R. R. Rao, C. A. Occhialini, J. Pelliciari, Y. Choi, T. Kawaguchi, H. You, J. F. Mitchell, Y. Shao-Horn, and R. Comin, Anomalous anti- ferromagnetism in metallic ruo 2 determined by resonant x-ray scattering, Phys. Rev. Lett.122, 017202 (2019)
work page 2019
-
[8]
N. Mehtougui, D. Rached, R. Khenata, H. Rached, M. Rabah, and S. Bin-Omran, Structural, electronic and mechanical properties of ruo2 from first-principles calcu- lations, Materials Science in Semiconductor Processing 15, 331 (2012)
work page 2012
-
[9]
L. ˇSmejkal, R. Gonz´ alez-Hern´ andez, T. Jungwirth, and J. Sinova, Crystal time-reversal symmetry breaking and spontaneous hall effect in collinear antiferromagnets, Sci- ence Advances6, eaaz8809 (2020)
work page 2020
- [10]
-
[11]
A. Smolyanyuk, I. I. Mazin, L. Garcia-Gassull, and R. Valent´ ı, Fragility of the magnetic order in the pro- totypical altermagnet ruo 2, Phys. Rev. B109, 134424 (2024)
work page 2024
-
[12]
K.-H. Ahn, A. Hariki, K.-W. Lee, and J. Kuneˇ s, Antifer- romagnetism in ruo 2 asd-wave pomeranchuk instability, Phys. Rev. B99, 184432 (2019)
work page 2019
-
[13]
Y. Sun, Y. Zhang, C.-X. Liu, C. Felser, and B. Yan, Dirac nodal lines and induced spin hall effect in metallic rutile oxides, Phys. Rev. B95, 235104 (2017)
work page 2017
- [14]
-
[15]
L. ˇSmejkal, J. Sinova, and T. Jungwirth, Beyond conven- tional ferromagnetism and antiferromagnetism: A phase with nonrelativistic spin and crystal rotation symmetry, Phys. Rev. X12, 031042 (2022)
work page 2022
-
[16]
L. ˇSmejkal, A. Marmodoro, K.-H. Ahn, R. Gonz´ alez- Hern´ andez, I. Turek, S. Mankovsky, H. Ebert, S. W. D’Souza, O. c. v. ˇSipr, J. Sinova, and T. c. v. Jungwirth, Chiral magnons in altermagnetic ruo 2, Phys. Rev. Lett. 131, 256703 (2023)
work page 2023
-
[17]
Z. Feng, X. Zhou, L. ˇSmejkal, L. Wu, Z. Zhu, H. Guo, R. Gonz´ alez-Hern´ andez, X. Wang, H. Yan, P. Qin, X. Zhang, H. Wu, H. Chen, Z. Meng, L. Liu, Z. Xia, J. Sinova, T. Jungwirth, and Z. Liu, An anomalous hall effect in altermagnetic ruthenium dioxide, Nature Elec- tronics5, 735 (2022)
work page 2022
-
[18]
T. Tschirner, P. Keßler, R. D. Gonzalez Betancourt, T. Kotte, D. Kriegner, B. B¨ uchner, J. Dufouleur, M. Kamp, V. Jovic, L. Smejkal, J. Sinova, R. Claessen, T. Jungwirth, S. Moser, H. Reichlova, and L. Veyrat, Saturation of the anomalous hall effect at high magnetic fields in altermagnetic ruo2, APL Materials11, 101103 (2023)
work page 2023
-
[19]
S. M. Hussain and K. Son, Exploring altermagnetism in ruo2: A review of a new paradigm in spintronics, Physica B: Condensed Matter716, 417723 (2025)
work page 2025
- [20]
-
[21]
O. Fedchenko, J. Min´ ar, A. Akashdeep, S. W. D’Souza, D. Vasilyev, O. Tkach, L. Odenbreit, Q. Nguyen, D. Kut- nyakhov, N. Wind, L. Wenthaus, M. Scholz, K. Ross- nagel, M. Hoesch, M. Aeschlimann, B. Stadtm¨ uller, M. Kl¨ aui, G. Sch¨ onhense, T. Jungwirth, A. B. Hellenes, G. Jakob, L. ˇSmejkal, J. Sinova, and H.-J. Elmers, Ob- servation of time-reversal s...
work page 2024
- [22]
-
[23]
J. Liu, J. Zhan, T. Li, J. Liu, S. Cheng, Y. Shi, L. Deng, M. Zhang, C. Li, J. Ding, Q. Jiang, M. Ye, Z. Liu, Z. Jiang, S. Wang, Q. Li, Y. Xie, Y. Wang, S. Qiao, J. Wen, Y. Sun, and D. Shen, Absence of altermagnetic spin splitting character in rutile oxide ruo 2, Phys. Rev. Lett.133, 176401 (2024)
work page 2024
-
[24]
T. Osumi, K. Yamauchi, S. Souma, S. Paul, A. Honma, K. Nakayama, K. Ozawa, M. Kitamura, K. Horiba, H. Kumigashira, C. Bigi, F. Bertran, T. Oguchi, T. Taka- hashi, Y. Maeno, and T. Sato, Spin-degenerate bulk bands and topological surface states associated with dirac nodal lines in ruo 2, Phys. Rev. B , (2026)
work page 2026
-
[25]
M. Wang, K. Tanaka, S. Sakai, Z. Wang, K. Deng, Y. Lyu, C. Li, D. Tian, S. Shen, N. Ogawa, N. Kanazawa, P. Yu, R. Arita, and F. Kagawa, Emergent zero-field anomalous hall effect in a reconstructed rutile anti- ferromagnetic metal, Nature Communications14, 8240 (2023)
work page 2023
- [26]
-
[27]
M. Hiraishi, H. Okabe, A. Koda, R. Kadono, T. Muroi, D. Hirai, and Z. Hiroi, Nonmagnetic ground state in ruo2 revealed by muon spin rotation, Phys. Rev. Lett.132, 166702 (2024)
work page 2024
-
[28]
[25, 26] for a de- tailed discussion
The apparent contradiction with earlier neutron and res- onant X-ray scattering results has been attributed to extrinsic effects, such as multiple scattering or sample- dependent structural defects; see Refs. [25, 26] for a de- tailed discussion
-
[29]
X. Peng, Z. Liu, S. Zhang, Y. Zhou, Y. Sun, Y. Su, C. Wu, T. Zhou, L. Liu, Y. Li, H. Wang, J. Yang, B. Chen, Y. Li, C. Xi, J. Du, Z. Jiao, Q. Wu, and M. Fang, Universal scaling behavior of transport prop- erties in non-magnetic ruo2, Communications Materials 6, 177 (2025)
work page 2025
- [30]
-
[32]
A. Smolyanyuk, L. ˇSmejkal, and I. I. Mazin, Origin of the anomalous hall effect in cr-doped ruo 2, Phys. Rev. B 111, 064406 (2025)
work page 2025
-
[33]
D. Q. Ho, D. Q. To, R. Hu, G. W. Bryant, and A. Jan- otti, Symmetry-breaking induced surface magnetization in nonmagnetic ruo2, Phys. Rev. Mater.9, 094406 (2025)
work page 2025
-
[34]
S. G. Jeong, S. Lee, B. Lin, Z. Yang, I. H. Choi, J. Y. Oh, S. Song, S. wook Lee, S. Nair, R. Choud- hary, J. Parikh, S. Park, W. S. Choi, J. S. Lee, J. M. LeBeau, T. Low, and B. Jalan, Metallicity and anomalous hall effect in epitaxially strained, atomically thin RuO 2 films, Proceedings of the Na- tional Academy of Sciences122, e2500831122 (2025), https...
-
[35]
C. A. Occhialini, L. G. P. Martins, S. Fan, V. Bisogni, T. Yasunami, M. Musashi, M. Kawasaki, M. Uchida, R. Comin, and J. Pelliciari, Strain-modulated anisotropic electronic structure in superconducting ruo 2 films, Phys. Rev. Mater.6, 084802 (2022)
work page 2022
-
[36]
K. Momma and F. Izumi,VESTA3for three-dimensional visualization of crystal, volumetric and morphology data, J. Appl. Crystallograph.44, 1272 (2011)
work page 2011
- [37]
-
[38]
J. Kuneˇ s, R. Arita, P. Wissgott, A. Toschi, H. Ikeda, and K. Held, Wien2wannier: From linearized augmented plane waves to maximally localized wannier functions, Computer Physics Communications181, 1888 (2010)
work page 2010
-
[39]
A. A. Mostofi, J. R. Yates, G. Pizzi, Y.-S. Lee, I. Souza, D. Vanderbilt, and N. Marzari, An updated version of wannier90: A tool for obtaining maximally-localised wannier functions, Computer Physics Communications 185, 2309 (2014)
work page 2014
-
[40]
M. Kawamura, Fermisurfer: Fermi-surface viewer provid- ing multiple representation schemes, Computer Physics Communications239, 197 (2018)
work page 2018
-
[41]
D. Csontosov´ a, K.-H. Ahn, and J. Kuneˇ s, Detailed study of the instability in ruo 2, Add (2026), see Supplemental Material at [URL] for additional details
work page 2026
-
[42]
Thus form a three dimensional subspace
-
[43]
Note that the leading instability ofχatQ z = 0 corre- sponds toQ z = 2πin the unfolded susceptibility ˜χ, while ˜χ(0) is the uniform susceptibility
-
[44]
Z. Wu, M. Long, H. Chen, S. Paul, H. Matsuki, O. Zhe- liuk, U. Zeitler, G. Li, R. Zhou, Z. Zhu, D. Graf, T. I. Weinberger, F. M. Grosche, Y. Maeno, and A. G. Eaton, Fermi surface of ruo2 measured by quantum oscillations, Phys. Rev. X15, 031044 (2025)
work page 2025
-
[45]
The deviations from [11] are due to larger HubbardUin that study
-
[46]
Efficient treatment of two-particle vertices in dynamical mean-field theory
D.-F. Shao, S.-H. Zhang, M. Li, C.-B. Eom, and E. Y. Tsymbal, Spin-neutral currents for spintronics, Nature Communications12, 7061 (2021). Supplemental material: Incipient magnetic instability in RuO 2 with random phase approximation Diana Csontosov´ a,1 Kyo-Hoon Ahn, 2 and Jan Kuneˇ s1 1Department of Condensed Matter Physics, Faculty of Science, Masaryk ...
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