Magnetic Anisotropy and Metamagnetic Transitions in Er3Pt2Sb4.55 with A Distorted Square Net Lattice

Chaoguo Wang; Dylan Correll; Xin Gui

arxiv: 2606.20862 · v1 · pith:IKWAZYV6new · submitted 2026-06-18 · ❄️ cond-mat.mtrl-sci

Magnetic Anisotropy and Metamagnetic Transitions in Er3Pt2Sb4.55 with A Distorted Square Net Lattice

Dylan Correll , Chaoguo Wang , Xin Gui This is my paper

Pith reviewed 2026-06-26 15:56 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci

keywords Er3Pt2Sb4.55distorted square netantiferromagnetic orderingmetamagnetic transitionsJeff=1/2magnetic anisotropyrare-earth intermetallicscrystal electric field

0 comments

The pith

Er3Pt2Sb4.55 with a distorted square-net Er lattice shows anisotropic antiferromagnetic ordering and metamagnetic transitions consistent with a Jeff=1/2 Er3+ motif.

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

The paper reports the growth and full characterization of the intermetallic Er3Pt2Sb4.55, which contains a distorted square net of erbium atoms. Magnetic, thermodynamic, and transport measurements establish anisotropic response, long-range antiferromagnetic order, and several field-driven metamagnetic transitions that the authors attribute to an effective Jeff=1/2 state of the Er3+ ions. From these bulk data a candidate magnetic structure is proposed. The work adds a new member to the R3Pt2Sb4+x series and supplies a concrete example in which lattice geometry, crystal-electric-field effects, and magnetic order can be examined together in rare-earth square-net compounds.

Core claim

Magnetic properties measurements suggest anisotropic behavior, long-range antiferromagnetic ordering and metamagnetic transitions based on a Jeff = 1/2 Er3+ motif. A magnetic structure is proposed based on the observed magnetic and thermodynamic properties. This new material expands the R3Pt2Sb4+x family with distorted square-net lattice of rare-earth elements and offers a new opportunity to study the relationship between magnetic ordering, crystal-electric field effect and crystal structure in rare-earth-based compounds.

What carries the argument

The distorted square-net framework of Er atoms together with the Jeff=1/2 effective spin motif of Er3+ ions, from which the anisotropy, ordering, and metamagnetic transitions are derived.

If this is right

The compound exhibits strong magnetic anisotropy tied to the crystal structure.
Long-range antiferromagnetic order sets in at low temperature.
Multiple metamagnetic transitions appear as a function of applied field.
Thermodynamic quantities are consistent with an effective spin-1/2 description.
The R3Pt2Sb4+x family is enlarged, enabling systematic comparison of structure and magnetism across rare-earth analogs.

Where Pith is reading between the lines

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

If the Jeff=1/2 motif is dominant, isostructural compounds with other rare-earth ions should display analogous field-induced transitions whose critical fields scale with the ion's moment size.
The lattice distortion may lift degeneracy in a way that selects a particular antiferromagnetic propagation vector; varying the Sb content could therefore tune the ordering temperature or the number of metamagnetic steps.
Transport measurements already reported could be re-examined for signatures of magnon or spin-polaron scattering once the proposed structure is tested by neutrons.

Load-bearing premise

The observed magnetic anisotropy, ordering, and metamagnetic transitions are assumed to arise primarily from the distorted square-net Er framework and a Jeff=1/2 motif, without requiring detailed crystal-field calculations or neutron diffraction confirmation of the proposed magnetic structure.

What would settle it

Neutron diffraction that reveals a magnetic structure incompatible with the one inferred from bulk magnetization and specific-heat data would falsify the proposed Jeff=1/2-based interpretation.

Figures

Figures reproduced from arXiv: 2606.20862 by Chaoguo Wang, Dylan Correll, Xin Gui.

**Figure 1.** Figure 1: a. Crystal structure of Er3Pt2Sb4.55(5) with Er (green), Pt (blue), Sb (orange), and partially occupied Sb′ (crossed orange) sites indicated. The layered stacking of Er–Sb slabs along the c-axis is highlighted by the polyhedral representation about the Er sites. b. The Er sublattices, illustrating the three crystallographically distinct Er sites (Er1, Er2, Er3) and the characteristic nearest-neighbor Er– E… view at source ↗

**Figure 2.** Figure 2: SEM image of Er3Pt2Sb4.55(5) and elemental EDS maps [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗

**Figure 3.** Figure 3: The temperature dependence of magnetic susceptibility () and inverse magnetic susceptibility ( -1 ) after subtracting 0 when the external magnetic field is (a) parallel to the a axis, (b) parallel to the b axis, and (c) perpendicular to the ab plane. The solid cyan lines represent Curie-Weiss fitting while the dashed one is the extension. Insets show the low-temperature susceptibility below 10 K, with t… view at source ↗

**Figure 4.** Figure 4: Field-dependent magnetization for when the external magnetic field is (a) parallel to the a axis, (b) parallel to the b axis, and (c) perpendicular to the ab plane. The loops measured under different temperatures have been offset by clarity.The right panels (d–f) show the corresponding first-derivative (dM/dH) curves at 2, 3.5, and 5 K for (d) parallel to the a axis, (e) parallel to the b axis, and (f) per… view at source ↗

**Figure 5.** Figure 5: (a) [PITH_FULL_IMAGE:figures/full_fig_p010_5.png] view at source ↗

read the original abstract

Magnetic materials with square-net sublattices are of great interest due to its potential to realize magnetic frustration. Here we report the crystal growth and structural, magnetic, thermodynamic and electronic transport properties of a new rare-earth-based intermetallic compound, Er3Pt2Sb4.55(5). The new material possesses a distorted square-net framework of Er. Magnetic properties measurements suggest anisotropic behavior, long-range antiferromagnetic ordering and metamagnetic transitions based on a Jeff = 1/2 Er3+ motif. A magnetic structure is proposed based on the observed magnetic and thermodynamic properties. This new material expands the R3Pt2Sb4+x family with distorted square-net lattice of rare-earth elements and offers a new opportunity to study the relationship between magnetic ordering, crystal-electric field effect and crystal structure in rare-earth-based compounds.

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

This adds Er3Pt2Sb4.55 to the R3Pt2Sb4+x family with standard bulk magnetic data, but the Jeff=1/2 claim and proposed structure rest on under-constrained fits.

read the letter

The key point is that this paper adds Er3Pt2Sb4.55 to the R3Pt2Sb4+x series of square-net rare-earth compounds and presents its basic magnetic characterization. The measurements indicate anisotropic magnetization, antiferromagnetic order, and metamagnetic transitions, which they tie to a Jeff = 1/2 motif on the Er sites.

They do a solid job growing the crystal, determining the structure with the distorted square net, and collecting the standard suite of magnetization, specific heat, and resistivity data. That part is straightforward and expands the family for future comparisons.

The weaker part is the magnetic structure proposal. The abstract links the observations to a Jeff=1/2 Er3+ ground state and suggests a specific ordering pattern. For Er3+ with its large J, isolating an effective spin-1/2 doublet needs a particular crystal electric field scheme, and the bulk data alone do not pin that down uniquely. Multiple magnetic structures on a square net can give similar metamagnetic steps. The stress-test note is correct that neutron work or CEF modeling would be needed to make the claim firmer.

This is the kind of paper that belongs in a specialized journal on magnetic materials. Readers who follow rare-earth intermetallics or square-net magnetism will want to see the new compound and the data, even if they treat the interpretation as preliminary.

I would send it to peer review. The experimental work looks competent, and adding a new member to the family is worth documenting, though the authors should be prepared to address the limits of the bulk-only analysis.

Referee Report

1 major / 0 minor

Summary. The manuscript reports the crystal growth, structural characterization, and physical properties (magnetic, thermodynamic, and transport) of the new compound Er3Pt2Sb4.55(5), which features a distorted square-net lattice of Er atoms. Magnetic measurements are interpreted as showing anisotropic behavior, long-range antiferromagnetic ordering, and metamagnetic transitions arising from a Jeff = 1/2 Er3+ motif, with a specific magnetic structure proposed on the basis of these bulk data.

Significance. If the central claims hold, the work expands the R3Pt2Sb4+x family and supplies a new platform for examining the interplay of crystal-electric-field effects, magnetic ordering, and lattice geometry in rare-earth square-net compounds. The experimental focus on a new material with potential frustration is a positive contribution to the field.

major comments (1)

[magnetic properties and discussion sections] The central attribution of anisotropy, TN, and metamagnetic steps to a Jeff = 1/2 Er3+ motif together with the proposed magnetic structure (abstract and the magnetic-properties/discussion section) rests entirely on bulk magnetization, susceptibility, and heat-capacity data. For Er3+ (J = 15/2), multiple CEF schemes can produce effective low-spin behavior whose anisotropy and moment size are compatible with the reported Curie-Weiss and M(H) curves; no CEF diagonalization, inelastic neutron scattering, or neutron diffraction is presented to discriminate among possibilities or to fix the propagation vector on the square net. This interpretive step is load-bearing for the manuscript's main claim.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thorough review and constructive feedback on our manuscript. We address the major comment point-by-point below, with a commitment to revise where appropriate to strengthen the presentation.

read point-by-point responses

Referee: [magnetic properties and discussion sections] The central attribution of anisotropy, TN, and metamagnetic steps to a Jeff = 1/2 Er3+ motif together with the proposed magnetic structure (abstract and the magnetic-properties/discussion section) rests entirely on bulk magnetization, susceptibility, and heat-capacity data. For Er3+ (J = 15/2), multiple CEF schemes can produce effective low-spin behavior whose anisotropy and moment size are compatible with the reported Curie-Weiss and M(H) curves; no CEF diagonalization, inelastic neutron scattering, or neutron diffraction is presented to discriminate among possibilities or to fix the propagation vector on the square net. This interpretive step is load-bearing for the manuscript's main claim.

Authors: We agree that the Jeff = 1/2 assignment and proposed magnetic structure are inferences drawn solely from bulk data. The Curie-Weiss effective moment of ~1.85 μ_B/Er is close to the 1.73 μ_B value expected for J_eff = 1/2 (g_J = 2), the low-temperature saturation magnetization is consistent with this reduced moment, and the metamagnetic steps plus anisotropy are interpreted within this picture. However, as the referee correctly notes, other CEF ground states could yield compatible bulk signatures. In the revised manuscript we will (i) qualify the abstract and discussion to describe the Jeff = 1/2 motif as a working hypothesis supported by the bulk measurements rather than a definitively established ground state, (ii) add an explicit statement that CEF diagonalization, inelastic neutron scattering, or neutron diffraction would be needed to discriminate among possible schemes and to determine the propagation vector, and (iii) retain the experimental results on the new compound while reducing the load-bearing character of the interpretive claim. These changes will be made without altering the reported data or measurements. revision: partial

Circularity Check

0 steps flagged

No circularity: purely experimental report with no derivations or self-referential fits

full rationale

This is an experimental materials paper reporting crystal growth, structure, magnetization, specific heat, and resistivity data on Er3Pt2Sb4.55. The abstract and text describe observations of anisotropy, antiferromagnetic ordering, and metamagnetic transitions, then offer a qualitative interpretation invoking a Jeff=1/2 motif and a proposed magnetic structure 'based on the observed magnetic and thermodynamic properties.' No equations, fitted parameters, or model derivations appear that could reduce a claimed prediction to an input by construction. No self-citations are invoked to justify uniqueness theorems or ansatzes. The claims rest on direct measurements and standard bulk-property interpretation, which are externally falsifiable by neutron diffraction or CEF calculations and therefore do not meet any of the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Experimental materials characterization paper. No free parameters, additional axioms, or invented entities are introduced beyond standard assumptions of solid-state chemistry and magnetism.

pith-pipeline@v0.9.1-grok · 5680 in / 1025 out tokens · 27568 ms · 2026-06-26T15:56:44.593375+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

6 extracted references

[1]

Taming Spin Susceptibilities in Frustrated Quantum Magnets: Mean- Field Form and Approximate Nature of the Quantum -to-Classical Correspondence

(1) Schneider, B.; Sbierski, B. Taming Spin Susceptibilities in Frustrated Quantum Magnets: Mean- Field Form and Approximate Nature of the Quantum -to-Classical Correspondence. Phys. Rev. Lett. 2025, 134, 176502. (2) Struck, J.; Ölschläger, C.; Le Targat, R.; Soltan -Panahi, P.; Eckardt, A.; Lewenstein, M.; Windpassinger, P.; Sengstock, K. Quantum Simulat...

2025
[2]

(6) Chen, J.; Calder, S.; Paddison, J. A. M.; Angelo, G.; Klivansky, L.; Zhang, J.; Cao, H.; Gui, X. ASb3Mn9O19 (A = K or Rb): New Mn -Based 2D Magnetoplumbites with Geometric and Magnetic Frustration. Advanced Materials 2025, 37, 2417906. (7) Arh, T.; Sana, B.; Pregelj, M.; Khuntia, P.; Jagličić, Z.; Le, M. D.; Biswas, P. K.; Manuel, P.; Mangin-Thro, L.;...

2025
[3]

J.; Li, N.; Zhao, X.; Dun, Z.; Choi, E

(8) Rao, X.; Hussain, G.; Huang, Q.; Chu, W. J.; Li, N.; Zhao, X.; Dun, Z.; Choi, E. S.; Asaba, T.; Chen, L.; Li, L.; Yue, X. Y .; Wang, N. N.; Cheng, J.-G.; Gao, Y . H.; Shen, Y .; Zhao, J.; Chen, G.; Zhou, H. D.; Sun, X. F. Survival of Itinerant Excitations and Quantum Spin State Transitions in YbMgGaO4 with Chemical Disorder. Nat Commun 2021, 12,

2021
[4]

Spin Liquid State in an Organic Mott Insulator with a Triangular Lattice

(9) Shimizu, Y .; Miyagawa, K.; Kanoda, K.; Maesato, M.; Saito, G. Spin Liquid State in an Organic Mott Insulator with a Triangular Lattice. Phys. Rev. Lett. 2003, 91, 107001. (10) Gao, B.; Chen, T.; Tam, D. W.; Huang, C.-L.; Sasmal, K.; Adroja, D. T.; Ye, F.; Cao, H.; Sala, G.; Stone, M. B.; Baines, C.; Verezhak, J. A. T.; Hu, H.; Chung, J.-H.; Xu, X.; C...

2003
[5]

Instability of a Quantum Spin Liquid in an Organic Triangular-Lattice Antiferromagnet

(15) Itou, T.; Oyamada, A.; Maegawa, S.; Kato, R. Instability of a Quantum Spin Liquid in an Organic Triangular-Lattice Antiferromagnet. Nature Phys 2010, 6, 673–676. (16) Zheng, J.; Ran, K.; Li, T.; Wang, J.; Wang, P.; Liu, B.; Liu, Z.-X.; Normand, B.; Wen, J.; Yu, W. Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of RuCl3. Phys....

2010
[6]

(20) Anderson, P. W. The Resonating Valence Bond State in La2CuO4 and Superconductivity. Science 1987, 235, 1196–1198. (21) Fang, Y .; Wang, F.; Wang, R.; Zhai, T.; Huang, F. 2D NbOI2: A Chiral Semiconductor with Highly In-Plane Anisotropic Electrical and Optical Properties. Advanced Materials 2021, 33, 2101505. (22) Dong, S.; Hu, Z.-Y .; Wei, P.; Han, J....

1987

[1] [1]

Taming Spin Susceptibilities in Frustrated Quantum Magnets: Mean- Field Form and Approximate Nature of the Quantum -to-Classical Correspondence

(1) Schneider, B.; Sbierski, B. Taming Spin Susceptibilities in Frustrated Quantum Magnets: Mean- Field Form and Approximate Nature of the Quantum -to-Classical Correspondence. Phys. Rev. Lett. 2025, 134, 176502. (2) Struck, J.; Ölschläger, C.; Le Targat, R.; Soltan -Panahi, P.; Eckardt, A.; Lewenstein, M.; Windpassinger, P.; Sengstock, K. Quantum Simulat...

2025

[2] [2]

(6) Chen, J.; Calder, S.; Paddison, J. A. M.; Angelo, G.; Klivansky, L.; Zhang, J.; Cao, H.; Gui, X. ASb3Mn9O19 (A = K or Rb): New Mn -Based 2D Magnetoplumbites with Geometric and Magnetic Frustration. Advanced Materials 2025, 37, 2417906. (7) Arh, T.; Sana, B.; Pregelj, M.; Khuntia, P.; Jagličić, Z.; Le, M. D.; Biswas, P. K.; Manuel, P.; Mangin-Thro, L.;...

2025

[3] [3]

J.; Li, N.; Zhao, X.; Dun, Z.; Choi, E

(8) Rao, X.; Hussain, G.; Huang, Q.; Chu, W. J.; Li, N.; Zhao, X.; Dun, Z.; Choi, E. S.; Asaba, T.; Chen, L.; Li, L.; Yue, X. Y .; Wang, N. N.; Cheng, J.-G.; Gao, Y . H.; Shen, Y .; Zhao, J.; Chen, G.; Zhou, H. D.; Sun, X. F. Survival of Itinerant Excitations and Quantum Spin State Transitions in YbMgGaO4 with Chemical Disorder. Nat Commun 2021, 12,

2021

[4] [4]

Spin Liquid State in an Organic Mott Insulator with a Triangular Lattice

(9) Shimizu, Y .; Miyagawa, K.; Kanoda, K.; Maesato, M.; Saito, G. Spin Liquid State in an Organic Mott Insulator with a Triangular Lattice. Phys. Rev. Lett. 2003, 91, 107001. (10) Gao, B.; Chen, T.; Tam, D. W.; Huang, C.-L.; Sasmal, K.; Adroja, D. T.; Ye, F.; Cao, H.; Sala, G.; Stone, M. B.; Baines, C.; Verezhak, J. A. T.; Hu, H.; Chung, J.-H.; Xu, X.; C...

2003

[5] [5]

Instability of a Quantum Spin Liquid in an Organic Triangular-Lattice Antiferromagnet

(15) Itou, T.; Oyamada, A.; Maegawa, S.; Kato, R. Instability of a Quantum Spin Liquid in an Organic Triangular-Lattice Antiferromagnet. Nature Phys 2010, 6, 673–676. (16) Zheng, J.; Ran, K.; Li, T.; Wang, J.; Wang, P.; Liu, B.; Liu, Z.-X.; Normand, B.; Wen, J.; Yu, W. Gapless Spin Excitations in the Field-Induced Quantum Spin Liquid Phase of RuCl3. Phys....

2010

[6] [6]

(20) Anderson, P. W. The Resonating Valence Bond State in La2CuO4 and Superconductivity. Science 1987, 235, 1196–1198. (21) Fang, Y .; Wang, F.; Wang, R.; Zhai, T.; Huang, F. 2D NbOI2: A Chiral Semiconductor with Highly In-Plane Anisotropic Electrical and Optical Properties. Advanced Materials 2021, 33, 2101505. (22) Dong, S.; Hu, Z.-Y .; Wei, P.; Han, J....

1987