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arxiv: 2605.25694 · v1 · pith:55W744OOnew · submitted 2026-05-25 · ❄️ cond-mat.str-el · cond-mat.mtrl-sci

Near-Room-Temperature Antiferromagnetic Ordering in the Quadruple Perovskite Sr4NaRu3O12

Subham Naik , Biswajit Singh , Hiranmayee Senapati , Akshay K. U. , Ramesh C. Nath , Soumyojit Chatterjee , Rahul Sharma , Thomas Doert
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Walter Schnelle Manfred Reehuis Thomas C. Hansen Michael Ruck Gohil S. Thakur
This is my paper

Pith reviewed 2026-06-29 20:43 UTC · model grok-4.3

classification ❄️ cond-mat.str-el cond-mat.mtrl-sci
keywords quadruple perovskiteantiferromagnetic orderingruthenium oxideneutron diffractionmagnetic structurecollinear spinssemiconductingSr4NaRu3O12
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The pith

Sr4NaRu3O12 orders antiferromagnetically below 265 K with collinear Ru moments along the c axis.

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

The paper reports the synthesis of Sr4NaRu3O12 as a 1:3 ordered quadruple perovskite in the centrosymmetric R-3 space group with a large unit cell. Magnetic susceptibility, differential scanning calorimetry, and neutron powder diffraction establish a transition to long-range antiferromagnetic order at TN approximately 265 K. The determined magnetic structure consists of collinear Ru spin alignment along the hexagonal c axis with propagation vector k equal to (0, 0, 1.5). Moments on Ru sites at the three-fold roto-inversion positions remain largely unpolarized due to geometric frustration between antiferromagnetically coupled neighbors. Complementary band-structure calculations reproduce both the observed antiferromagnetic ground state and semiconducting electronic behavior.

Core claim

Sr4NaRu3O12 crystallizes in space group R-3 with Na and Ru ordered on the B sites, forming only corner-connected RuO6 and NaO6 octahedra and yielding a unit cell with a equal to 11.25 angstroms and c equal to 27.6 angstroms. It undergoes a transition to an antiferromagnetic state below TN approximately 265 K. The Ru moments adopt a collinear antiferromagnetic arrangement along the hexagonal c axis with propagation vector k equal to (0, 0, 1.5). Moments lying on the three-fold roto-inversion axis do not contribute appreciably to the order because they sit between antiferromagnetically coupled Ru atoms and are therefore highly frustrated. Band-structure calculations on the compound are consist

What carries the argument

The 1:3 B-site ordered quadruple perovskite structure of corner-connected RuO6 and NaO6 octahedra that stabilizes collinear antiferromagnetic order with propagation vector k = (0, 0, 1.5) at 265 K.

If this is right

  • The Ru moments on three-fold roto-inversion sites remain largely unpolarized owing to frustration between neighboring antiferromagnetically aligned spins.
  • The compound is semiconducting in its antiferromagnetic state according to both experiment and band-structure calculations.
  • Sr4LiRu3O12, prepared under the same protocol, exhibits a magnetic anomaly at a lower temperature near 110 K that may arise from competing ferromagnetic and antiferromagnetic interactions.
  • The large unit cell arising from Na/Ru ordering produces a magnetic propagation vector that is commensurate with the hexagonal lattice.

Where Pith is reading between the lines

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

  • The near-room-temperature transition temperature implies that the strength of the dominant Ru-Ru superexchange interaction is unusually large for an oxide perovskite.
  • Selective ordering on the Ru sublattice may allow chemical substitution on the frustrated sites to tune the balance between ordered and disordered magnetism.
  • The same synthesis route that yields the Na compound could be used to test whether other alkali-metal substitutions raise or lower the ordering temperature in isostructural quadruple perovskites.

Load-bearing premise

The neutron diffraction data and magnetic measurements correctly identify long-range collinear antiferromagnetic order rather than short-range correlations, impurity phases, or competing interactions that could mimic the observed transition.

What would settle it

Absence of magnetic Bragg peaks at positions generated by the propagation vector k = (0, 0, 1.5) in neutron diffraction data collected below 265 K would falsify the reported long-range magnetic structure.

Figures

Figures reproduced from arXiv: 2605.25694 by Akshay K. U., Biswajit Singh, Gohil S. Thakur, Hiranmayee Senapati, Manfred Reehuis, Michael Ruck, Rahul Sharma, Ramesh C. Nath, Soumyojit Chatterjee, Subham Naik, Thomas C. Hansen, Thomas Doert, Walter Schnelle.

Figure 1
Figure 1. Figure 1: Le Bail fit of room temperature PXRD data of Sr4NaRu3O12 (a) and Sr4LiRu3O12 (b). Blue and red curves are observed and calculated intensities and black line is their difference. Green vertical bars indicate allowed reflections. Inset of (a) shows the SEM image of a typical Sr4NaRu3O12 crystal. The crystal structure of Sr4NaRu3O12 is displayed in [PITH_FULL_IMAGE:figures/full_fig_p007_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: XPS data of Sr4NaRu3O12. The binding energy (B.E.) value for Ru(VI) is taken from Sr3Ru2O8(OH)2, which has been recently confirmed experimentally.63,64 XPS spectra of RuO2 and KRuO4 were recorded on commercially available samples. From the nominal composition, an oxidation state close to +5 is expected for ruthenium. To confirm this, we performed XPS studies, the detailed results of which are presented in … view at source ↗
Figure 4
Figure 4. Figure 4: (a) Logarithm of resistivity plotted against T 1/4 for Sr4NaRu3O12; inset displays the ln vs T 1 curve (b)  vs T curve and its first derivative exhibiting a sharp dip at T ~ 260 K. temperature interval and yields a small apparent activation energy of about 50 meV. This value should not be equated directly with the intrinsic band gap, because the full temperature dependence is better described by 3D var… view at source ↗
Figure 5
Figure 5. Figure 5: Magnetic properties of Sr4NaRu3O12: (a) magnetic susceptibility in the T-range 2 - 700 K at different applied field, inset showing the magnified region near the magnetic transition (b) magnetic susceptibility in ZFC and FC protocols at an applied field of 0.1 T (c) straight line fit to the inverse susceptibility (d) magnetic hysteresis loop collected at 2 K. A small increase in susceptibility below 170 K, … view at source ↗
Figure 6
Figure 6. Figure 6: Magnetic properties and heat capacity of Sr4LiRu3O12: (a) magnetic susceptibility in the T￾range 2 - 750 K at different applied fields, inset showing the magnified ZFC and FC data near the magnetic transition. (b) Straight line fit to the inverse susceptibility at 𝜇0𝐻 = 0.5 T. Inset shows 𝜒𝑇 vs T at the same field. (c) Magnetic hysteresis loop collected at 1.8 K. (d) Cp vs T data collected at zero applied … view at source ↗
Figure 8
Figure 8. Figure 8: figure 8 [PITH_FULL_IMAGE:figures/full_fig_p015_8.png] view at source ↗
read the original abstract

We report the synthesis, structure and magnetic properties of two 1:3 ordered quadruple perovskites Sr4MRu3O12 (M = Li and Na). Sr4NaRu3O12 crystallizes in the centrosymmetric space group R-3 and Sr4LiRu3O12 appears to be isostructural to the Na compound based on the PXRD data. In Sr4NaRu3O12, both Na and Ru are predominantly ordered at the B sites (here Na/Li and Ru) and the structure contains only corner-connected RuO6 and NaO6 octahedra. This atomic ordering also leads to a rather large unit cell with a = 11.25 {\AA} and c = 27.6 {\AA} compared to the basic 12R structure (a = 5.5 {\AA} and c ~ 27 {\AA}). Magnetic measurements reveal that Sr4NaRu3O12 undergoes a magnetic transition to an antiferromagnetic state below TN ~ 265 K which is confirmed by DSC and neutron diffraction. The Ru moments show a collinear antiferromagnetic spin alignment along the hexagonal c axis with a propagation vector k = (0, 0, 1.5). Interestingly, those Ru moments lying on the three-fold roto-inversion do not significantly contribute to the magnetic order, since they are located between antiferromagnetically coupled Ru atoms and are therefore probably highly frustrated. Band structure calculations on Sr4NaRu3O12 complement the observed magnetic ground state and a semiconducting behavior in the compound. Sr4LiRu3O12 shows a magnetic anomaly below 110 K, possibly associated with competing ferromagnetic and antiferromagnetic interactions.

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 the synthesis and structural characterization of the quadruple perovskites Sr4NaRu3O12 (space group R-3, a=11.25 Å, c=27.6 Å) and Sr4LiRu3O12. For the Na compound it claims a transition to long-range collinear antiferromagnetic order below TN ≈ 265 K with propagation vector k=(0,0,1.5), Ru moments aligned along the hexagonal c-axis, and suppressed moments on the three-fold roto-inversion sites; this is supported by magnetic susceptibility, DSC, and neutron diffraction. Complementary DFT calculations indicate a semiconducting antiferromagnetic ground state. The Li analog is reported to show a magnetic anomaly near 110 K possibly arising from competing interactions.

Significance. If the reported near-room-temperature antiferromagnetic ordering and its detailed magnetic structure are confirmed, the result would constitute a notable addition to the limited set of quadruple perovskites exhibiting high TN, offering a platform to study frustration on the three-fold sites and the role of B-site ordering. The multi-technique experimental approach (susceptibility, DSC, neutron diffraction) together with band-structure calculations is a strength of the work.

major comments (2)
  1. [Neutron diffraction] Neutron diffraction section: the central claim of long-range collinear AF order with k=(0,0,1.5) and suppressed moments on the 3-fold sites rests on the peak indexing and magnetic refinement; the manuscript must report the magnetic R-factor, the fitted moment values with uncertainties, and an explicit test that alternative propagation vectors or short-range models do not fit the data equally well.
  2. [Magnetic properties] Magnetic properties section: the susceptibility and DSC data establishing TN ~ 265 K require a quantitative discussion of possible impurity phases (noted as 'predominantly' ordered in the abstract) and their potential contribution to the observed transition, including any low-temperature upturns or additional anomalies.
minor comments (2)
  1. [Abstract] The abstract states that moments on the three-fold roto-inversion sites 'do not significantly contribute'; this should be tied explicitly to the Wyckoff positions and the refined moment values in the neutron section.
  2. [Figures and tables] Figure captions and text should consistently report error bars or uncertainties on TN, lattice parameters, and magnetic moments.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the positive assessment of our work and the constructive comments. We address each major comment below and will revise the manuscript accordingly.

read point-by-point responses

  1. Referee: [Neutron diffraction] Neutron diffraction section: the central claim of long-range collinear AF order with k=(0,0,1.5) and suppressed moments on the 3-fold sites rests on the peak indexing and magnetic refinement; the manuscript must report the magnetic R-factor, the fitted moment values with uncertainties, and an explicit test that alternative propagation vectors or short-range models do not fit the data equally well.

    Authors: We agree that these quantitative details are required to fully support the claimed magnetic structure. In the revised manuscript we will report the magnetic R-factor, the refined moment values with uncertainties, and an explicit comparison showing that alternative propagation vectors and short-range models yield significantly worse fits to the neutron data. revision: yes

  2. Referee: [Magnetic properties] Magnetic properties section: the susceptibility and DSC data establishing TN ~ 265 K require a quantitative discussion of possible impurity phases (noted as 'predominantly' ordered in the abstract) and their potential contribution to the observed transition, including any low-temperature upturns or additional anomalies.

    Authors: We will expand the magnetic properties section to include a quantitative discussion of possible impurity phases, their estimated volume fractions, and an assessment of any contribution they may make to the transition at TN ≈ 265 K or to low-temperature features in the susceptibility and DSC data. revision: yes

Circularity Check

0 steps flagged

No significant circularity; experimental report with independent data

full rationale

The manuscript is an experimental report of synthesis, PXRD structure solution, magnetic susceptibility, DSC, and neutron powder diffraction on Sr4NaRu3O12. The central claim of collinear antiferromagnetic order below TN ≈ 265 K with propagation vector k = (0,0,1.5) is established directly by indexing of magnetic Bragg peaks and Rietveld refinement of the magnetic structure against the neutron data; no equations, fitted parameters, or self-citations are invoked to derive this result from itself. Band-structure calculations are presented only as complementary confirmation of semiconducting behavior and are not used to predict or justify the magnetic ordering. No self-definitional, fitted-input-called-prediction, or self-citation-load-bearing steps exist. The derivation chain is therefore self-contained against external experimental benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on standard assumptions from crystallography and neutron scattering rather than new postulates; no free parameters or invented entities are introduced in the abstract.

axioms (2)
  • domain assumption Powder X-ray diffraction and Rietveld analysis reliably determine the R-3 space group and Na/Ru site ordering.
    Invoked to establish the atomic structure and large unit cell.
  • standard math Neutron diffraction peaks can be indexed to a magnetic propagation vector k=(0,0,1.5) to confirm long-range antiferromagnetic order.
    Used to identify the collinear spin alignment and frustrated sites.

pith-pipeline@v0.9.1-grok · 5915 in / 1469 out tokens · 28142 ms · 2026-06-29T20:43:44.794125+00:00 · methodology

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Reference graph

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