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arxiv: 2509.02475 · v1 · submitted 2025-09-02 · ❄️ cond-mat.str-el · cond-mat.mes-hall· cond-mat.mtrl-sci

Signatures of three-state Potts nematicity in spin excitations of the van der Waals antiferromagnet FePSe₃

Pith reviewed 2026-05-18 19:44 UTC · model grok-4.3

classification ❄️ cond-mat.str-el cond-mat.mes-hallcond-mat.mtrl-sci
keywords FePSe3three-state Potts nematicityzigzag antiferromagnetspin excitationsneutron scatteringvan der Waals materialsmagnetoelastic couplingvestigial order
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The pith

Spin excitations in FePSe3 retain broken threefold symmetry slightly above the zigzag antiferromagnetic ordering temperature.

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

The paper uses neutron scattering to examine how uniaxial strain affects the magnetic order and spin excitations in the van der Waals antiferromagnet FePSe3. It finds that modest tensile strain selects two out of three zigzag domains, reducing both the order and the excitations to twofold rotational symmetry. This reduced symmetry in the spin excitations continues into the paramagnetic phase just above the Néel temperature of 108.6 K. The results indicate that the three-state Potts nematicity arises as vestigial order tied to the low-temperature zigzag antiferromagnetic state through magnetoelastic coupling. A sympathetic reader would care because the finding links magnetic ordering to electronic symmetry breaking in two-dimensional materials without requiring separate electronic instabilities.

Core claim

In the antiferromagnetically ordered state, application of approximately 0.6 percent tensile strain suppresses one zigzag domain and promotes the other two, which lowers the symmetry of the antiferromagnetic order and the spin waves to C2. The broken C3 symmetry observed in the spin excitations persists slightly above TN approximately 108.6 K, even though the zigzag antiferromagnetic order has disappeared. These measurements supply direct evidence of magnetoelastic coupling and imply that the three-state Potts nematicity detected in the paramagnetic spin excitations originates from the vestigial order associated with the low-temperature zigzag antiferromagnetic order.

What carries the argument

Uniaxial-strain-induced selection among zigzag domains that produces a persistent C2 symmetry in the spin excitations above the Néel temperature, detected by neutron scattering.

If this is right

  • Strain provides a practical handle for selecting specific zigzag domains and thereby controlling the symmetry of spin waves in FePSe3.
  • Magnetoelastic coupling transmits the symmetry breaking of the low-temperature order into the paramagnetic regime.
  • The three-state Potts nematicity is not an independent electronic phase but a vestigial consequence of the zigzag antiferromagnetic order.
  • Similar domain-selection and symmetry-persistence effects are expected in other honeycomb-lattice van der Waals antiferromagnets under strain.

Where Pith is reading between the lines

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

  • The same vestigial-order mechanism could account for nematic signatures seen in other two-dimensional magnets that lack obvious electronic driving forces.
  • Experiments that apply strain only in the paramagnetic phase could test whether the nematic response requires proximity to the ordered state.
  • The results suggest that elastic control of spin excitations may be feasible in related materials for potential spintronic or magnonic applications.

Load-bearing premise

The observed persistence of C2 symmetry in spin excitations above TN is produced by vestigial three-state Potts nematic order rather than by residual short-range magnetic correlations or by strain-induced shifts in exchange parameters that have nothing to do with nematicity.

What would settle it

A measurement showing that spin excitations recover full C3 symmetry above TN when uniaxial strain is removed, or when short-range correlations are eliminated by temperature or doping while strain is still applied.

Figures

Figures reproduced from arXiv: 2509.02475 by Bin Gao, Devashibhai Adroja, Pengcheng Dai, Ruixian Liu, Sijie Xu, S. J. Gomez Alvarado, Viviane Pe\c{c}anha Antonio, Weiliang Yao, Xingye Lu.

Figure 1
Figure 1. Figure 1: (d)]. In neutron diffraction, ZZ1, ZZ2, and ZZ3 do￾mains contribute to magnetic Bragg peaks at the three M-points of the hexagonal Brillouin zone [M1, M2, and M3 in the inset of [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. (a) Elastic scattering pattern of the ( [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (a) and (b) Spin excitation spectra along [ [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
read the original abstract

In two-dimensional (2D) nearly square-lattice quantum materials, electron correlations can induce an electronic nematic phase with twofold rotational ($C_2$) symmetry that profoundly impacts their properties. For 2D materials with threefold rotational ($C_3$) symmetry, such as the honeycomb lattice, a vestigial three-state Potts nematic order has been observed in the van der Waals antiferromagnet (AFM) FePSe$_3$ via optical and thermodynamic methods under uniaxial strain. Here, we use neutron scattering to study the magnetic order and spin excitations of FePSe$_3$ under uniaxial strain. In the AFM ordered state, we find that $\sim$0.6% tensile strain significantly suppresses one zigzag domain and promotes the other two, lowering the AFM order and spin waves to $C_2$ symmetry. The broken $C_3$ symmetry in spin excitations persists slightly above $T_{\rm{N}}\approx 108.6$ K, where the zigzag AFM order is absent. Our results thus provide direct evidence of magnetoelastic coupling and suggest that the three-state Potts nematicity in paramagnetic spin excitations arises from the vestigial order associated with the low-temperature zigzag AFM order.

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 neutron scattering measurements on the van der Waals antiferromagnet FePSe₃ under uniaxial strain. It finds that ~0.6% tensile strain suppresses one zigzag AFM domain while promoting the other two, reducing both the magnetic order and spin-wave excitations to C₂ symmetry. The central claim is that this broken C₃ symmetry in the spin excitations persists slightly above T_N ≈ 108.6 K (where long-range zigzag order vanishes), providing evidence of magnetoelastic coupling and indicating that the three-state Potts nematicity in the paramagnetic phase is a vestigial order tied to the low-temperature AFM state.

Significance. If the interpretation is robust, the work supplies momentum-resolved neutron data that directly links strain-tuned domain populations to symmetry breaking in spin excitations, extending prior optical and thermodynamic observations of vestigial Potts nematicity. The experimental approach of applying uniaxial strain while tracking both ordered and paramagnetic regimes is a clear strength and offers a concrete test of magnetoelastic effects in a C₃-symmetric honeycomb lattice material. The absence of quantitative controls, however, leaves the distinction between true vestigial order and alternative strain-induced short-range correlations unresolved.

major comments (2)
  1. [Abstract] Abstract (final sentence) and discussion of paramagnetic regime: The claim that the observed C₂ anisotropy above T_N constitutes direct evidence of vestigial three-state Potts nematic order is not quantitatively supported. No temperature scaling of the anisotropy relative to the magnetic correlation length, nor any comparison to nematic susceptibility, is presented to rule out strain-modified exchange parameters or short-range zigzag fluctuations that themselves break C₃ symmetry in the paramagnetic state.
  2. [Results (paramagnetic phase)] Results on spin excitations above T_N: The intensity maps and dispersion relations showing persistent C₂ symmetry lack reported error bars, background-subtraction procedures, and control data taken without applied strain. These omissions prevent a clear assessment of whether the high-temperature C₂ signal is intrinsic or arises from residual short-range correlations or experimental artifacts.
minor comments (2)
  1. [Methods/Figure captions] The strain value (~0.6%) and its orientation relative to the honeycomb lattice should be stated more explicitly in the methods or figure captions to allow direct comparison with theoretical models of magnetoelastic coupling.
  2. [Experimental details] A brief statement on the instrumental resolution and any corrections applied to the spin-wave data would improve clarity without altering the central claims.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the thoughtful and constructive review of our manuscript. The comments help clarify the presentation of our evidence for vestigial three-state Potts nematicity. Below we respond point by point to the major comments. We have revised the manuscript to address the concerns where possible while maintaining the integrity of our experimental claims.

read point-by-point responses
  1. Referee: [Abstract] Abstract (final sentence) and discussion of paramagnetic regime: The claim that the observed C₂ anisotropy above T_N constitutes direct evidence of vestigial three-state Potts nematic order is not quantitatively supported. No temperature scaling of the anisotropy relative to the magnetic correlation length, nor any comparison to nematic susceptibility, is presented to rule out strain-modified exchange parameters or short-range zigzag fluctuations that themselves break C₃ symmetry in the paramagnetic state.

    Authors: We agree that a quantitative scaling analysis would further strengthen the interpretation. However, the selective suppression of one zigzag domain under strain, which directly imprints C₂ symmetry onto the spin excitations both below and above T_N, is difficult to reconcile with uniform strain-modified exchange parameters (which would not preferentially select domains). Short-range zigzag fluctuations in the paramagnetic state would also be expected to average over all three domains in the absence of strain, yet our data show the anisotropy only appears under the same strain conditions that select domains in the ordered phase. We have added a dedicated paragraph in the revised discussion section that qualitatively compares the temperature dependence of the anisotropy to the magnetic correlation length extracted from the quasielastic scattering and explicitly contrasts the observations with strain-renormalized exchange scenarios. A full quantitative nematic susceptibility analysis lies beyond the present dataset but is noted as a direction for future work. revision: partial

  2. Referee: [Results (paramagnetic phase)] Results on spin excitations above T_N: The intensity maps and dispersion relations showing persistent C₂ symmetry lack reported error bars, background-subtraction procedures, and control data taken without applied strain. These omissions prevent a clear assessment of whether the high-temperature C₂ signal is intrinsic or arises from residual short-range correlations or experimental artifacts.

    Authors: We thank the referee for pointing out these presentational gaps. In the revised manuscript we have added statistical error bars to all intensity maps and dispersion cuts in the paramagnetic regime. The background-subtraction procedure (using empty-can measurements scaled to the sample volume and temperature) is now described in the Methods section with explicit reference to the supplementary figures. Control data without applied strain are shown in Supplementary Figure S3, demonstrating that the spin excitations remain C₃-symmetric in the unstrained paramagnetic phase; the C₂ anisotropy appears only when uniaxial strain is applied. These additions allow the reader to assess that the high-temperature signal is not an artifact. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental symmetry observations are direct measurements, not derived from fitted inputs or self-citations

full rationale

The manuscript presents neutron scattering intensity maps, dispersion relations, and domain populations in FePSe3 under applied strain. These are reported as raw experimental results (e.g., suppression of one zigzag domain and persistence of C2 symmetry slightly above TN). No equations, ansatze, or predictions are introduced that reduce by construction to a fitted parameter, a self-citation chain, or a renamed empirical pattern. The interpretation linking the data to vestigial three-state Potts nematicity is offered as a suggestion supported by prior optical/thermodynamic work, but the central claims remain independent measurements that can be checked against the reported spectra and temperature dependence without circular reduction.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The claim rests on standard assumptions of neutron scattering as a probe of magnetic correlations and on the interpretation that domain selection under strain directly reveals vestigial nematic order; no new entities or free parameters are introduced.

axioms (2)
  • domain assumption Neutron scattering intensity maps spin-wave dispersion and domain populations in antiferromagnets
    Invoked implicitly when the authors attribute changes in scattering to domain suppression and symmetry lowering.
  • domain assumption Uniaxial strain couples to magnetic anisotropy via magnetoelastic interaction
    Used to explain why 0.6% tensile strain selects specific zigzag domains.

pith-pipeline@v0.9.0 · 5807 in / 1270 out tokens · 38358 ms · 2026-05-18T19:44:21.662525+00:00 · methodology

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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/Foundation/AlexanderDuality.lean alexander_duality_circle_linking unclear
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    Relation between the paper passage and the cited Recognition theorem.

    The broken C3 symmetry in spin excitations persists slightly above TN≈108.6 K, where the zigzag AFM order is absent, providing direct evidence of magnetoelastic coupling and suggesting that the three-state Potts nematicity arises from the vestigial order associated with the low-temperature zigzag AFM order.

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matches
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extends
The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
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contradicts
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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

48 extracted references · 48 canonical work pages

  1. [1]

    A. J. Beekman, L. Rademaker, and J. van Wezel, SciPost Phys. Lect. Notes , 11 (2019)

  2. [2]

    N. W. Ashcroft and N. D. Mermin, Solid State Physics (Holt-Saunders, New York, 1976)

  3. [3]

    De Gennes and J

    P.-G. De Gennes and J. Prost, The physics of liquid crys- tals, 83 (Oxford University Press, 1993)

  4. [4]

    S. A. Kivelson, E. Fradkin, and V. J. Emery, Nature 393, 550 (1998)

  5. [5]

    Fradkin, S

    E. Fradkin, S. A. Kivelson, M. J. Lawler, J. P. Eisenstein, and A. P. Mackenzie, Annu. Rev. Condens. Matter Phys. 1, 153 (2010)

  6. [6]

    R. M. Fernandes, P. P. Orth, and J. Schmalian, Annual Review of Condensed Matter Physics 10, 133 (2019)

  7. [7]

    L. Nie, G. Tarjus, and S. A. Kivelson, Proceedings of 6 the National Academy of Sciences 111, 7980 (2014)

  8. [8]

    Dai, Rev

    P. Dai, Rev. Mod. Phys. 87, 855 (2015)

  9. [9]

    A. E. B¨ ohmer, J.-H. Chu, S. Lederer, and M. Yi, Nature Physics 18, 1412 (2022)

  10. [10]

    Hinkov, D

    V. Hinkov, D. Haug, B. Fauqu´ e, P. Bourges, Y. Sidis, A. Ivanov, C. Bernhard, C. T. Lin, and B. Keimer, Sci- ence 319, 597 (2008)

  11. [11]

    J.-H. Chu, J. G. Analytis, K. D. Greve, P. L. McMahon, Z. Islam, Y. Yamamoto, and I. R. Fisher, Science 329, 824 (2010)

  12. [12]

    Since the nematic state retains C2 symmetry, the distinctions be- tween C3 and C6 symmetries become irrelevant, render- ing them effectively equivalent in this context

    In two-dimensional systems of interest, the C6 group can be generated by the C3 and C2 subgroups. Since the nematic state retains C2 symmetry, the distinctions be- tween C3 and C6 symmetries become irrelevant, render- ing them effectively equivalent in this context

  13. [13]

    R. M. Fernandes and J. W. F. Venderbos, Science Ad- vances 6, eaba8834 (2020)

  14. [14]

    A. R. Chakraborty and R. M. Fernandes, Phys. Rev. B 107, 195136 (2023)

  15. [15]

    Y. Xie, A. Hardy, and A. Paramekanti, Phys. Rev. B 110, 165158 (2024)

  16. [16]

    Little, C

    A. Little, C. Lee, C. John, S. Doyle, E. Maniv, N. L. Nair, W. Chen, D. Rees, J. W. Venderbos, R. M. Fernandes, J. G. Analytis, and J. Orenstein, Nature Materials 19, 1062 (2020)

  17. [17]

    Z. Feng, W. Lu, T. Lu, F. Liu, J. R. Sheeran, M. Ye, J. Xia, T. Kurumaji, and L. Ye, arXiv preprint arXiv:2507.05486 (2025)

  18. [18]

    Kirstein, P

    E. Kirstein, P. Park, W. Cho, C. D. Batista, J.-G. Park, and S. A. Crooker, arXiv preprint arXiv:2507.08148 (2025)

  19. [19]

    L. Nie, K. Sun, W. Ma, D. Song, L. Zheng, Z. Liang, P. Wu, F. Yu, J. Li, M. Shan, D. Zhao, S. Li, B. Kang, Z. Wu, Y. Zhou, K. Liu, Z. Xiang, J. Ying, Z. Wang, T. Wu, and X. Chen, Nature 604, 59 (2022)

  20. [20]

    Y. Xu, Z. Ni, Y. Liu, B. R. Ortiz, Q. Deng, S. D. Wilson, B. Yan, L. Balents, and L. Wu, Nature physics 18, 1470 (2022)

  21. [21]

    Asaba, A

    T. Asaba, A. Onishi, Y. Kageyama, T. Kiyosue, K. Oht- suka, S. Suetsugu, Y. Kohsaka, T. Gaggl, Y. Kasahara, H. Murayama, K. Hashimoto, R. Tazai, H. Kontani, B. R. BR Ortiz, S. D. Wilson, Q. Li, H.-H. Wen, T. Shibauchi, and Y. Matsuda, Nature Physics 20, 40 (2024)

  22. [22]

    Farhang, W

    C. Farhang, W. R. Meier, W. Lu, J. Li, Y. Wu, S. Mozaf- fari, R. P. Madhogaria, Y. Zhang, D. Mandrus, and J. Xia, Nature Communications 16, 7867 (2025)

  23. [23]

    Hwangbo, E

    K. Hwangbo, E. Rosenberg, J. Cenker, Q. Jiang, H. Wen, D. Xiao, J.-H. Chu, and X. Xu, Nature Physics 20, 1888 (2024)

  24. [24]

    Z. Ni, D. S. Antonenko, W. J. Meese, Q. Tian, N. Huang, A. V. Haglund, M. Cothrine, D. G. Mandrus, R. M. Fernandes, J. W. Venderbos, J. W. F. Venderbos, and W. Liang, arXiv preprint arXiv:2308.07249 (2023)

  25. [25]

    Q. Tan, C. A. Occhialini, H. Gao, J. Li, H. Kitadai, R. Comin, and X. Ling, Nano Letters 24, 7166 (2024)

  26. [26]

    Taylor, J

    B. Taylor, J. Steger, A. Wold, and E. Kostiner, Inorganic Chemistry 13, 2719 (1974)

  27. [27]

    Q. H. Wang, A. Bedoya-Pinto, M. Blei, A. H. Dismukes, A. Hamo, S. Jenkins, M. Koperski, Y. Liu, Q.-C. Sun, E. J. Telford, H. H. Kim, M. Augustin, U. Vool, J.- X. Yin, L. H. Li, A. Falin, C. R. Dean, F. Casanova, R. F. L. Evans, M. Chshiev, A. Mishchenko, C. Petrovic, R. He, L. Zhao, A. W. Tsen, B. D. Gerardot, M. Brotons- Gisbert, Z. Guguchia, X. Roy, S. ...

  28. [28]

    J. Cui, E. V. Bostr¨ om, M. Ozerov, F. Wu, Q. Jiang, J.- H. Chu, C. Li, F. Liu, X. Xu, A. Rubio, A. Rubio, and Q. Zhang, Nature Communications 14, 3396 (2023)

  29. [29]

    Haglund, Thermal conductivity of MXY 3 magnetic layered trichalcogenides, Ph.D

    A. Haglund, Thermal conductivity of MXY 3 magnetic layered trichalcogenides, Ph.D. thesis, University of Ten- nessee, Knoxville, TN (2019), ph.D. dissertation

  30. [30]

    L. Chen, X. Teng, D. Hu, F. Ye, G. E. Granroth, M. Yi, J.-H. Chung, R. J. Birgeneau, and P. Dai, npj Quantum Materials 9, 40 (2024)

  31. [31]

    Wiedenmann, J

    A. Wiedenmann, J. Rossat-Mignod, A. Louisy, R. Brec, and J. Rouxel, Solid State Communications 40, 1067 (1981)

  32. [32]

    Bhutani, J

    A. Bhutani, J. L. Zuo, R. D. McAuliffe, C. R. dela Cruz, and D. P. Shoemaker, Phys. Rev. Mater. 4, 034411 (2020)

  33. [33]

    Z. Mo, C. Li, W. Zhang, C. Liu, Y. Sun, R. Liu, and X. Lu, Chinese Physics Letters 41, 107102 (2024)

  34. [34]

    Toth and B

    S. Toth and B. Lake, Journal of Physics: Condensed Mat- ter 27, 166002 (2015)

  35. [35]

    X. Lu, J. T. Park, R. Zhang, H. Luo, A. H. Nevidomskyy, Q. Si, and P. Dai, Science 345, 657 (2014)

  36. [36]

    M. G. Kim, R. M. Fernandes, A. Kreyssig, J. W. Kim, A. Thaler, S. L. Bud’ko, P. C. Canfield, R. J. McQueeney, J. Schmalian, and A. I. Goldman, Phys. Rev. B 83, 134522 (2011)

  37. [37]

    Lu, K.-F

    X. Lu, K.-F. Tseng, T. Keller, W. Zhang, D. Hu, Y. Song, H. Man, J. T. Park, H. Luo, S. Li, A. H. Nevidomskyy, and P. Dai, Phys. Rev. B 93, 134519 (2016)

  38. [38]

    P. Liu, M. L. Klemm, L. Tian, X. Lu, Y. Song, D. W. Tam, K. Schmalzl, J. Park, Y. Li, G. Tan, Y. Su, F. Bour- darot, Y. Zhao, J. W. Lynn, R. J. Birgeneau, and P. Dai, Nature Communications 11, 5728 (2020)

  39. [39]

    D. W. Tam, W. Wang, L. Zhang, Y. Song, R. Zhang, S. V. Carr, H. C. Walker, T. G. Perring, D. T. Adroja, and P. Dai, Phys. Rev. B 99, 134519 (2019)

  40. [40]

    R. Liu, M. B. Stone, S. Gao, M. Nakamura, K. Ka- mazawa, A. Krajewska, H. C. Walker, P. Cheng, R. Yu, Q. Si, P. Dai, and X. Lu, Nature Communications 16, 5212 (2025)

  41. [41]

    See Supplemental Material [url] for additional data and analyses

  42. [42]

    Bewley, R

    R. Bewley, R. Eccleston, K. McEwen, S. Hayden, M. Dove, S. Bennington, J. Treadgold, and R. Coleman, Physica B: Condensed Matter 385-386, 1029 (2006)

  43. [43]

    X. Lu, W. Zhang, Y. Tseng, R. Liu, Z. Tao, E. Paris, P. Liu, T. Chen, V. N. Strocov, Y. Song, R. Yu, Q. Si, P. Dai, and T. Schmitt, Nature Physics 18, 806 (2022)

  44. [44]

    Lane and M

    H. Lane and M. Mourigal, Phys. Rev. B 111, 174446 (2025)

  45. [45]

    Basnet, T

    R. Basnet, T. Patel, J. Wang, D. Upreti, S. K. Chhetri, G. Acharya, M. R. U. Nabi, J. Sakon, and J. Hu, Ad- vanced Electronic Materials 10, 2300738 (2024)

  46. [46]

    Arnold et al

    O. Arnold et al. , Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 764, 156 (2014)

  47. [47]

    Ewings, A

    R. Ewings, A. Buts, M. Le, J. van Duijn, I. Bustinduy, and T. Perring, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 834, 132 (2016)

  48. [48]

    Signatures of three-state Potts nematicity in spin excitations of the van der Waals antiferromagnet FePSe 3

    G. Xu, Z. Xu, and J. M. Tranquada, Review of Scientific Instruments 84, 083906 (2013). 1 Supplemental Material for “Signatures of three-state Potts nematicity in spin excitations of the van der Waals antiferromagnet FePSe 3” I. FEPSE 3 SINGLE CR YST AL GROWTH AND CHARACTERIZA TION High-quality FePSe3 single crystals were synthesized using a chemical vapor...