Crystal structure and the magnetic properties of the 5d transition metal oxide AOsO4 (A = K, Rb, Cs)

Jun-ichi Yamaura; Zenji Hiroi

arxiv: 1906.08519 · v1 · pith:WAIMISPOnew · submitted 2019-06-20 · ❄️ cond-mat.str-el · cond-mat.mtrl-sci

Crystal structure and the magnetic properties of the 5d transition metal oxide AOsO4 (A = K, Rb, Cs)

Jun-ichi Yamaura , Zenji Hiroi This is my paper

Pith reviewed 2026-05-25 19:22 UTC · model grok-4.3

classification ❄️ cond-mat.str-el cond-mat.mtrl-sci

keywords 5d transition metal oxidesscheelite structureantiferromagnetismstructural phase transitionmagnetic susceptibilityOs7+ compoundsdiamond lattice

0 comments

The pith

K and Rb AOsO4 order antiferromagnetically while Cs AOsO4 shows a structural transition with a halved Os moment.

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

The paper reports synthesis of the 5d1 oxides AOsO4 for A equal to K, Rb and Cs and determines that they adopt scheelite or quasi-scheelite structures built from distorted diamond lattices of tetrahedrally coordinated Os7+ ions that lack local inversion symmetry. Magnetic and heat-capacity data show that the K and Rb members undergo antiferromagnetic transitions at 36.9 K and 21.0 K with Weiss temperatures of -66 K and -18 K and effective moments of 1.44-1.45 mu_B per Os. The Cs member instead displays a positive Weiss temperature of +12 K, a reduced moment of only 0.8 mu_B per Os, no magnetic order above 2 K, and a first-order structural transition at 152.5 K. The authors attribute the suppressed moment, especially in the Cs case, to an antiparallel orbital contribution even though spin-orbit coupling is expected to be quenched within the low-lying e orbitals.

Core claim

The K and Rb compounds order antiferromagnetically below 36.9 K and 21.0 K with effective moments near 1.45 mu_B, whereas CsOsO4 undergoes a first-order structural transition at 152.5 K, exhibits a positive Weiss temperature and no magnetic order above 2 K, and displays a strongly reduced moment of 0.8 mu_B that is ascribed to an antiparallel orbital moment.

What carries the argument

Distorted diamond lattice of Os7+ (d1) ions in tetrahedral oxide coordination without local inversion symmetry, which permits antisymmetric spin-orbit coupling and is probed through the contrasting magnetic responses across the alkali series.

If this is right

The size of the alkali cation tunes the balance between antiferromagnetic order and lattice instability in these 5d1 tetrahedral systems.
Antisymmetric spin-orbit coupling arising from the broken inversion symmetry is available to shape the magnetic interactions.
Deviation of the effective moment from the spin-only d1 value signals orbital participation that survives the expected quenching in the e manifold.

Where Pith is reading between the lines

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

The structural transition in the Cs compound may be driven by the same lattice degrees of freedom that suppress magnetic order, suggesting a magnetoelastic competition tunable by external pressure.
Related 5d1 compounds with tetrahedral coordination could exhibit similar moment reductions if the alkali or ligand size is adjusted to approach the Cs limit.
Absence of inversion symmetry opens the possibility that Dzyaloshinskii-Moriya terms contribute to the observed antiferromagnetic ordering temperatures in the K and Rb members.

Load-bearing premise

The reduced Os moment originates from an antiparallel orbital moment rather than from covalency, disorder or experimental artifacts.

What would settle it

Direct measurement of the Os orbital and spin moments, for example by XMCD or polarized neutron diffraction, that either confirms or rules out an antiparallel orbital contribution of the size needed to explain the observed effective moments.

read the original abstract

We synthesized the 5d1-transition metal oxides AOsO4 (A = K, Rb, Cs) by solid-state reaction, and performed structure determination and magnetic and heat capacity measurements. It was found that they crystallize in a scheelite (A = K and Rb) or a quasi-scheelite structure (A = Cs) comprising of distorted diamond lattices of septivalent Os (d1) ions tetrahedrally coordinated by four oxide ions without local inversion symmetry; hence an antisymmetric spin-orbit coupling is expected in the crystals. The K and Rb compounds have Weiss temperatures of theta = -66 and -18 K, effective magnetic moments of mu_eff = 1.44 and 1.45 mu_B/Os, and antiferromagnetic transition temperatures of T_N = 36.9 and 21.0 K, respectively. In contrast, the Cs compound has theta = 12 K and mu_eff = 0.8 mu_B/Os without magnetic transition above 2 K, instead exhibiting a first-order structural transition at T_s = 152.5 K. The decline of the Os moment from 1.73 mu_B/Os for the simple d1 spin, particularly for Cs, is likely to originate from the antiparallel orbital moment, although the spin-orbit coupling is generally quenched in the low-lying e orbitals.

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

New synthesis and magnetic data for three 5d1 osmates, with clean measurements but only a tentative note on the reduced moment.

read the letter

The main takeaway is that the authors made KOsO4, RbOsO4, and CsOsO4 by solid-state reaction and measured their structures plus basic magnetic and heat-capacity properties. K and Rb versions order antiferromagnetically at 36.9 K and 21 K with Weiss temperatures of -66 K and -18 K and effective moments of 1.44-1.45 muB. The Cs version shows a first-order structural transition at 152.5 K, a positive Weiss temperature, a much smaller moment of 0.8 muB, and no magnetic order above 2 K. These specific numbers and the scheelite-type structures with tetrahedral Os are new to the literature they cite. The experimental work is straightforward and the data support the reported transition temperatures and fitted parameters without obvious gaps or inconsistencies. Powder XRD, susceptibility curves, and heat-capacity anomalies are standard observables that line up with the claims. The structures confirm the expected diamond-like Os lattices without local inversion symmetry, which sets up the possibility of antisymmetric spin-orbit coupling, though the paper does not pursue that further. The one softer part is the brief suggestion that the reduced moment, especially in Cs, likely comes from an antiparallel orbital contribution. They qualify it as likely and note that spin-orbit coupling is usually quenched in the e orbitals, but there are no neutron or XMCD data to test it. This is an interpretive aside rather than a load-bearing claim, so it does not affect the validity of the measured quantities. The paper is aimed at people who follow new 5d oxide compounds and their magnetism. The central results are direct and reproducible in principle, with no circular fitting or invented parameters. It deserves a serious referee because the compounds and their measured properties are new and the experimental section is solid.

Referee Report

0 major / 2 minor

Summary. The manuscript reports the solid-state synthesis of AOsO4 (A = K, Rb, Cs), powder X-ray structure determination showing scheelite (K, Rb) or quasi-scheelite (Cs) structures with tetrahedral OsO4 units on a distorted diamond lattice, and bulk magnetic susceptibility plus heat-capacity data. Extracted parameters include Weiss temperatures θ = −66 K (K), −18 K (Rb), +12 K (Cs); effective moments μ_eff = 1.44, 1.45, and 0.8 μ_B/Os respectively; antiferromagnetic ordering at T_N = 36.9 K (K) and 21.0 K (Rb); and a first-order structural transition at T_s = 152.5 K (Cs) with no magnetic order above 2 K. The reduced Os moment relative to the spin-only d1 value is noted as likely arising from an antiparallel orbital contribution.

Significance. The work supplies well-documented experimental examples of 5d1 oxides in tetrahedral coordination without local inversion symmetry. The reported synthesis routes, lattice parameters, susceptibility curves, and transition temperatures are standard observables that directly support the stated values and allow comparison with other 5d and 4d systems. The data are internally consistent and do not rely on derived parameters or self-referential modeling.

minor comments (2)

Abstract and final paragraph: the attribution of the reduced moment to an antiparallel orbital contribution is explicitly qualified as 'likely,' which is appropriate; however, a short sentence in the discussion section clarifying why other mechanisms (covalency, site disorder) are considered less probable would strengthen the interpretive remark without altering the experimental claims.
Experimental section: the description of the Curie-Weiss fitting window and any temperature range used for the linear regime should be stated explicitly so that the reported θ and μ_eff values can be reproduced from the raw data.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for the positive evaluation of our manuscript on the synthesis, structure, and magnetic properties of AOsO4 (A = K, Rb, Cs). The referee's recommendation to accept is appreciated, and we note that no specific revisions or major comments were raised.

Circularity Check

0 steps flagged

No circularity; all results are direct experimental measurements and standard fits

full rationale

The paper reports solid-state synthesis of AOsO4 compounds, powder XRD for scheelite/quasi-scheelite structures, and magnetic/heat-capacity data yielding Weiss temperatures, mu_eff values, and transition temperatures via conventional Curie-Weiss analysis and anomaly detection. No equations, predictions, or derivations appear; the single interpretive sentence on orbital moment is explicitly qualified as 'likely' and is not required for the measured quantities. No self-citations, ansatzes, or fitted inputs renamed as predictions are present.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on standard experimental assumptions of solid-state chemistry and magnetometry rather than new theoretical postulates or fitted parameters.

axioms (2)

domain assumption Standard assumptions of solid-state synthesis and powder X-ray diffraction for phase identification and structure solution
Invoked for determining scheelite versus quasi-scheelite structures and confirming phase purity.
domain assumption Curie-Weiss law applicability to extract theta and mu_eff from susceptibility data above ordering temperatures
Used to report Weiss temperatures and effective moments.

pith-pipeline@v0.9.0 · 5793 in / 1617 out tokens · 32003 ms · 2026-05-25T19:22:34.880783+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

The decline of the Os moment from 1.73 μ_B/Os for the simple d1 spin, particularly for Cs, is likely to originate from the antiparallel orbital moment, although the spin–orbit coupling is generally quenched in the low-lying e orbitals.
IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

We synthesized the 5d1-transition metal oxides AOsO4 (A = K, Rb, Cs) by solid-state reaction, and performed structure determination and magnetic and heat capacity measurements.

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

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K. Momma and F. Izumi, J. Appl. Crystallogr. 44, 1272 (2011). 14 TABLE I. Crystallographic data for AOsO4 at 300 K. The structural parameters are refined with the I41/a (#88) space group for KOsO 4 and RbOsO4, and Pnma (#62) for CsOsO 4. The atomic positions and Wyckoff letters (W. L.) are also given [23]. Aom W. L. x y z K; a = 5.65206(5) Å, c = 12.6642(...

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[1] [1]

B. J. Kim, H. Ohsumi, T. Komesu, S. Sakai, T. Morita, H. Takagi, and T. Arima, Science 323, 1329 (2009)

work page 2009

[2] [2]

Jackeli and G

G. Jackeli and G. Khaliullin, Phys. Rev. Lett. 102, 017205 (2009)

work page 2009

[3] [3]

Kitaev, Ann

A. Kitaev, Ann. Phys. (N.Y .) 321, 2 (2006)

work page 2006

[4] [4]

Yamaura, K

J. Yamaura, K. Ohgushi, H. Ohsumi, T. Hasegawa, I. Yamauchi, K. Sugimoto, S. Takeshita, A. Tokuda, M. Takata, M. Udagawa, M. Takigawa, H. Harima, T. Arima, and Z. Hiroi, Phys. Rev. Lett. 108, 247205 (2012)

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[5] [5]

Shinaoka, T

H. Shinaoka, T. Miyake, and S. Ishibashi, Phys. Rev. Lett. 108, 247204 (2012)

work page 2012

[6] [6]

Calder, J

S. Calder, J. G. Vale, N. A. Bogdanov, X. Liu, C. Donnerer, M. H. Upton, D. Casa, A. H. Said, M. D. Lumsden, Z. Zhao, J. -Q. Yan, D. Mandrus, S. Nishimoto, J. van den Brink, J. P. H ill, D. F. McMorrow, and A. D. Christianson, Nat. Commun. 7, 11651 (2016)

work page 2016

[7] [7]

Tomiyasu, K

K. Tomiyasu, K. Matsuhira, K. Iwasa, M. Watahiki, S. Takagi, M. Wakeshima, Y . Hinatsu, M. 12 Yokoyama, K. Ohoyama, and K. Yamada, J. Phys. Soc. Jpn. 81, 034709 (2012)

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[8] [8]

Sagayama, D

H. Sagayama, D. Uematsu, T. Arima, K. Sugimoto, J. J. Ishikawa, E. O’Farrell, and S. Nakatsuji, Phys. Rev. B 87, 100403(R) (2013)

work page 2013

[9] [9]

H. J. Xiang and M.-H. Whangbo, Phys. Rev. B 75, 052407 (2007)

work page 2007

[10] [10]

A. S. Erickson, S. Misra, G. J. Miller, R. R. Gupta, Z. Schle singer, W. A. Harrison, J. M. Kim, and I. R. Fisher, Phys. Rev. Lett. 99, 016404 (2007)

work page 2007

[11] [11]

Lee and W

K.-W. Lee and W. E. Pickett, Europhys. Lett. 80, 37008 (2007)

work page 2007

[12] [12]

Hiroi, J

Z. Hiroi, J. Yamaura, T. C. Kobayashi, Y . Matsubayashi, and D. Hirai, J. Phys. Soc. Jpn. 87, 024702 (2017)

work page 2017

[13] [13]

J. W. Harter, Z. Y . Zhao, J. Q. Yan, D. G. Mandrus, and D. Hsieh, Science 356, 295 (2017)

work page 2017

[14] [14]

Yamaura, K

J. Yamaura, K. Takeda, Y . Ikeda, N. Hirao, Y . Ohishi, T. C. Kobayashi, and Z. Hiroi, Phys. Rev. B 95, 020102(R) (2017)

work page 2017

[15] [15]

Song, K.-H

Y .-J. Song, K.-H. Ahn, K.-W. Lee, and W. E. Pickett, Phys. Rev. B 90, 245117 (2014)

work page 2014

[16] [16]

Hayami, H

S. Hayami, H. Kusunose, and Y . Motome, Phys. Rev. B 97, 024414 (2018)

work page 2018

[17] [17]

R. G. Dickinson, J. Am. Chem. Soc. 42, 85 (1920)

work page 1920

[18] [18]

Zhang, N

Y . Zhang, N. A. W. Holzwarth, and R. T. Williams, Phys. Rev. B 57, 12738 (1998)

work page 1998

[19] [19]

Levason, M

W. Levason, M. Tajik, and M. Webster, J. Chem. Soc. Dalton Trans. 1735 (1985)

work page 1985

[20] [20]

Beintema, Z

J. Beintema, Z. für Kristallogr. Kristallgeo. Kristallphy. Kristallchem. 97, 300 (1937)

work page 1937

[21] [21]

Izumi and K

F. Izumi and K. Momma, Solid State Phenom. 130, 15 (2007)

work page 2007

[22] [22]

Krebs and K.-D

B. Krebs and K.-D. Hasse, Acta Crystallogr. B 32, 1334 (1976)

work page 1976

[23] [23]

International Tables for Crystallography, ed. T. Hahn (Kluwer Academic, Dordrecht, 2002) 4th ed., V ol. A

work page 2002

[24] [24]

C. A. Marjerrison, C. Mauws, A. Z. Sharma, C. R. Wiebe, S. Derakhshan, C. Boyer, B. D. Gaulin, and J. E. Greedan, Inorg. Chem. 55, 12897 (2016)

work page 2016

[25] [25]

L. J. de Jongh and A. R. Miedema, Adv. Phys. 23, 1 (1974). 13

work page 1974

[26] [26]

Oitmaa, J

J. Oitmaa, J. Phys: Condens. Matter 30, 155801 (2018)

work page 2018

[27] [27]

M. Huse, A. W. B. Skilbred, M. Karlsson, S. G. Eriksson, T. Norby, R. Haugsrud, and C. S. Knee, J. Solid State Chem. 187, 27 (2012)

work page 2012

[28] [28]

Sarin, R

P. Sarin, R. W. Hughes, D. R. Lowry, Z. D. Apostolov, and W. M. Kriven, J. Am. Ceram. Soc. 97, 3307 (2014)

work page 2014

[29] [29]

Momma and F

K. Momma and F. Izumi, J. Appl. Crystallogr. 44, 1272 (2011). 14 TABLE I. Crystallographic data for AOsO4 at 300 K. The structural parameters are refined with the I41/a (#88) space group for KOsO 4 and RbOsO4, and Pnma (#62) for CsOsO 4. The atomic positions and Wyckoff letters (W. L.) are also given [23]. Aom W. L. x y z K; a = 5.65206(5) Å, c = 12.6642(...

work page 2011