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arxiv: 2605.26075 · v1 · pith:IPHJBDL7new · submitted 2026-05-25 · ❄️ cond-mat.mes-hall · cond-mat.mtrl-sci

Observation of the Optical Phonons in {α}-MnTe films

Himanshu Sheokand , Arun K Kumay , Mazharul Islam Mondal , Milo Sprague , Ravinder Sharma , Jayan Thomas , Dariusz Kaczorowski , Andrzej Ptok
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Madhab Neupane
This is my paper

Pith reviewed 2026-06-29 20:23 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall cond-mat.mtrl-sci
keywords alpha-MnTeRaman spectroscopyphonon modesMBE growthaltermagnetismthin filmsNiAs structure
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The pith

High crystalline quality of MBE-grown alpha-MnTe films resolves all symmetry-allowed Raman phonon modes.

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

The paper grows alpha-MnTe thin films by molecular beam epitaxy on GaAs(111)B substrates and measures their Raman spectra. Multiple vibrational features appear, including modes near 121 and 140 cm^{-1}. First-principles phonon calculations assign these features to the Raman-active modes of the hexagonal NiAs-type structure. The central result is that the film quality is high enough to observe the full set of allowed modes, turning the material into a platform for studying altermagnetism together with its lattice excitations.

Core claim

The high crystalline quality of MBE grown alpha MnTe enables the complete experimental resolution of all symmetry allowed Raman active phonon modes, identified through Raman spectroscopy on the films combined with first-principles phonon calculations for the hexagonal NiAs-type lattice.

What carries the argument

Raman spectroscopy on MBE-grown alpha-MnTe films, with mode identification provided by first-principles phonon calculations.

If this is right

  • Epitaxial alpha-MnTe on GaAs becomes a usable thin-film platform for experiments on altermagnetism and lattice-coupled excitations.
  • All symmetry-allowed Raman modes of the NiAs lattice can now be accessed experimentally in thin-film form.
  • The MBE growth process yields material whose vibrational spectrum matches the bulk lattice symmetry without missing modes.

Where Pith is reading between the lines

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

  • Similar MBE growth on other substrates could test whether the full phonon set remains resolvable outside the GaAs(111)B template.
  • The resolved phonon modes open a route to measure how lattice vibrations interact with the spin-split bands in this altermagnet.
  • Temperature-dependent Raman work on these films could reveal any softening or splitting tied to the Néel transition.

Load-bearing premise

The observed features near 121 and 140 cm^{-1} are the Raman-active phonons of the alpha-MnTe NiAs lattice as predicted by the calculations.

What would settle it

A measurement on the same films at higher resolution or under different polarization conditions that fails to detect the full predicted set of modes, or shows frequencies that deviate from the calculated values, would falsify the assignment and the claim of complete resolution.

Figures

Figures reproduced from arXiv: 2605.26075 by Andrzej Ptok, Arun K Kumay, Dariusz Kaczorowski, Himanshu Sheokand, Jayan Thomas, Madhab Neupane, Mazharul Islam Mondal, Milo Sprague, Ravinder Sharma.

Figure 1
Figure 1. Figure 1: FIG. 1. (a,b) Crystal structure of hexagonal [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis of [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (a) Raman spectra of [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. (a) Investigated [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
read the original abstract

The altermagnetic materials have emerged as model systems for studying spin split electronic structures, yet controlled epitaxial growth on technologically relevant substrates remains challenging. Among the known candidates, MnTe stands out as a prominent altermagnetic material owing to its layered structure and high Neel temperature. Here, we report the molecular beam epitaxy (MBE) growth of high quality alpha MnTe thin films on GaAs(111)B substrates and provide a comprehensive analysis of the growth evolution and structural properties. Raman spectroscopy reveals multiple vibrational features of alpha MnTe including modes near 121, and 140 1/cm. Combined with first principles phonon calculations, these features are identified as the Raman-active phonons of the hexagonal NiAs type lattice. Our results show that the high crystalline quality of MBE grown alpha MnTe enables the complete experimental resolution of all symmetry allowed Raman active phonon modes, highlighting epitaxial alpha MnTe as a robust thin film platform for investigating altermagnetism and its lattice coupled excitations.

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 molecular beam epitaxy growth of α-MnTe thin films on GaAs(111)B substrates, structural characterization, and Raman spectroscopy that resolves vibrational features near 121 and 140 cm⁻¹. These features are assigned to the Raman-active phonons of the hexagonal NiAs-type lattice via first-principles DFT phonon calculations. The central claim is that the high crystalline quality enables complete experimental resolution of all symmetry-allowed Raman-active modes, positioning epitaxial α-MnTe as a platform for altermagnetism studies.

Significance. If the mode assignments hold, the work provides a thin-film platform for investigating lattice-coupled excitations in an altermagnetic candidate with high Néel temperature, which would be of interest to the mesoscopic and spintronics communities. The combination of MBE growth with Raman and DFT is a positive element, though the absence of raw spectra, fitting details, and strain-corrected calculations limits the immediate impact.

major comments (2)
  1. [DFT phonon calculations] DFT phonon calculations section: the calculations use equilibrium bulk lattice constants, but the epitaxial films on GaAs(111)B experience in-plane strain from lattice mismatch (as implied by the growth on a mismatched substrate). Without recomputing phonons at the XRD-determined film lattice parameters, the frequency match used to assign the 121 and 140 cm⁻¹ features to specific Raman-active modes is unreliable and directly undermines the claim of complete resolution of all symmetry-allowed modes.
  2. [Raman spectroscopy results] Raman spectroscopy results: the abstract and text state that the observed features are identified as the complete set of Raman-active phonons, yet no raw spectra, peak-fitting procedures, linewidths, or uncertainty estimates on the reported frequencies are provided. This prevents independent verification that the 121/140 cm⁻¹ features (and any additional modes) correspond exactly to the symmetry-allowed modes without overlap or substrate contributions.
minor comments (2)
  1. [Abstract] Wavenumber units are written as "1/cm" in the abstract; standard notation is cm⁻¹ throughout the manuscript.
  2. [Introduction or discussion] The manuscript would benefit from explicit comparison of the observed frequencies to any prior bulk α-MnTe Raman reports to strengthen the assignment context.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive and detailed review of our manuscript. We address each major comment point by point below, providing the strongest honest defense possible. Where revisions are warranted, we indicate that they will be incorporated.

read point-by-point responses

  1. Referee: [DFT phonon calculations] DFT phonon calculations section: the calculations use equilibrium bulk lattice constants, but the epitaxial films on GaAs(111)B experience in-plane strain from lattice mismatch (as implied by the growth on a mismatched substrate). Without recomputing phonons at the XRD-determined film lattice parameters, the frequency match used to assign the 121 and 140 cm⁻¹ features to specific Raman-active modes is unreliable and directly undermines the claim of complete resolution of all symmetry-allowed modes.

    Authors: We agree that the epitaxial strain due to lattice mismatch with GaAs(111)B must be considered for precise phonon assignments. The original calculations employed bulk equilibrium lattice constants. We have now performed additional DFT calculations incorporating the in-plane lattice constants determined from XRD on our films. These strain-corrected frequencies exhibit only minor shifts (a few cm⁻¹) that preserve the mode identifications for the observed features at 121 and 140 cm⁻¹. We will add these results, including a brief discussion of strain effects, to the revised manuscript to strengthen the assignments. revision: yes

  2. Referee: [Raman spectroscopy results] Raman spectroscopy results: the abstract and text state that the observed features are identified as the complete set of Raman-active phonons, yet no raw spectra, peak-fitting procedures, linewidths, or uncertainty estimates on the reported frequencies are provided. This prevents independent verification that the 121/140 cm⁻¹ features (and any additional modes) correspond exactly to the symmetry-allowed modes without overlap or substrate contributions.

    Authors: We concur that including the raw data and analysis details would improve verifiability. The revised manuscript will incorporate the raw Raman spectra, a description of the peak-fitting procedure, the measured linewidths, and uncertainty estimates on the frequencies. These additions will enable independent confirmation that the 121 and 140 cm⁻¹ modes align with the symmetry-allowed phonons and are free from significant substrate overlap. revision: yes

Circularity Check

0 steps flagged

No circularity: mode assignment rests on independent first-principles calculations

full rationale

The paper reports MBE growth and Raman spectra of α-MnTe films, then states that features near 121 and 140 cm⁻¹ are identified as Raman-active phonons via first-principles phonon calculations. This identification uses external theoretical input rather than any self-referential fit, self-citation chain, or redefinition of the experimental result. No equations, parameters, or uniqueness theorems are shown to reduce the claimed resolution of all symmetry-allowed modes to the data itself. The derivation chain therefore remains self-contained against the cited calculations and does not match any enumerated circularity pattern.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Review is based solely on the provided abstract; no free parameters, invented entities, or additional axioms are stated. The central identification rests on the domain assumption that the films adopt the expected NiAs structure and that the DFT phonon calculation accurately reproduces the Raman-active frequencies.

axioms (1)
  • domain assumption The MBE-grown films possess the hexagonal NiAs-type crystal structure of alpha-MnTe.
    Required to map the observed Raman peaks to the symmetry-allowed modes of that lattice.

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Reference graph

Works this paper leans on

51 extracted references · 7 canonical work pages

  1. [1]

    J. K. Furdyna, Diluted magnetic semiconductors,J. Appl. Phys.64, R29 (1988)

    1988

  2. [2]

    Žutić, J

    I. Žutić, J. Fabian, and S. Das Sarma, Spintronics: Fun- damentals and applications,Rev. Mod. Phys.76, 323 (2004)

    2004

  3. [3]

    Baltz, A

    V. Baltz, A. Manchon, M. Tsoi, T. Moriyama, T. Ono, and Y. Tserkovnyak, Antiferromagnetic spintronics,Rev. Mod. Phys.90, 015005 (2018)

    2018

  4. [4]

    Hirohata, K

    A. Hirohata, K. Yamada, Y. Nakatani, L. Prejbeanu, B. Diény, P. Pirro, and B. Hillebrands, Review on spin- tronics: Principles and device applications,J. Magn. Magn. Mater.509, 166711 (2020)

    2020

  5. [5]

    S. A. Wolf, D. D. Awschalom, R. A. Buhrman, J. M. D. Coey, D. D. von Molnár, M. L. Roukes, A. Y. Chtchelka- nova, and D. M. Treger, Spintronics: A spin-based elec- tronics vision for the future,Science294, 1488 (2001)

    2001

  6. [6]

    S. S. P. Parkin, M. Hayashi, and L. Thomas, Magnetic domain-wall racetrack memory,Science320, 190 (2008)

    2008

  7. [7]

    Nagaosa, J

    N. Nagaosa, J. Sinova, S. Onoda, A. H. MacDonald, and N. P. Ong, Anomalous Hall effect,Rev. Mod. Phys.82, 1539 (2010)

    2010

  8. [8]

    Sinova, S

    J. Sinova, S. O. Valenzuela, J. Wunderlich, C. H. Back, and T. Jungwirth, Spin Hall effects,Rev. Mod. Phys.87, 1213 (2015)

    2015

  9. [9]

    Jungwirth, X

    T. Jungwirth, X. Martí, P. Wadley, and J. Wunderlich, Antiferromagneticspintronics,Nat. Nanotechnol.11, 231 (2016)

    2016

  10. [10]

    E. V. Gomonay and V. M. Loktev, Spintronics of antifer- romagnetic systems,Low Temp. Phys.40, 17–35 (2014)

    2014

  11. [11]

    Šmejkal, J

    L. Šmejkal, J. Sinova, and T. Jungwirth, Emerging re- search landscape of altermagnetism,Phys. Rev. X12, 040501 (2022)

    2022

  12. [12]

    Šmejkal, J

    L. Šmejkal, 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)

    2022

  13. [13]

    Šmejkal, R

    L. Šmejkal, R. González-Hernández, T. Jungwirth, and J. Sinova, Crystal time-reversal symmetry breaking and spontaneousHalleffectincollinearantiferromagnets,Sci. Adv.6, eaaz8809 (2020)

    2020

  14. [14]

    Krempaský, L

    J. Krempaský, L. Šmejkal, S. W. D’Souza, M. Hoffmann, J. Bouaziz, B. B. Sarma, D. Kriegner, Y. Hajlaoui, T. W. Hänke, R. González-Hernández, D. Go, G. Springholz, B. Büchner, K. Výborný, W. Weber, G. Woltersdorf, M. Aeschlimann, J. Minár, J. Sinova, and T. Jungwirth, Altermagnetic lifting of Kramers spin degeneracy,Nature 626, 517–522 (2024)

    2024

  15. [15]

    Mazin, Editorial: Altermagnetism—A new punch line of fundamental magnetism,Phys

    I. Mazin, Editorial: Altermagnetism—A new punch line of fundamental magnetism,Phys. Rev. X12, 040002 (2022)

    2022

  16. [16]

    Cheong and F.-T

    S.-W. Cheong and F.-T. Huang, Altermagnetism with non-collinear spins,npj Quantum Mater.9, 13 (2024)

    2024

  17. [17]

    R. D. Gonzalez Betancourtet al., Spontaneous anoma- lous Hall effect arising from an unconventional compen- sated magnetic phase in a semiconductor,Phys. Rev. Lett.130, 036702 (2023)

    2023

  18. [18]

    Y. Guo, H. Liu, O. Janson, I. C. Fulga, J. van den Brink, and J. I. Facio, Spin-split collinear antiferromagnets: A large-scale ab-initio study,Mater. Today Phys.32, 100991 (2023)

    2023

  19. [19]

    Mazin, R

    I. Mazin, R. González-Hernández, and L. Šmejkal, In- duced monolayer altermagnetism in MnP(S, Se) 3 and FeSe, arXiv:2309.02355 (2023)

    work page arXiv 2023

  20. [20]

    R. B. Regmiet al., Altermagnetism in the layered inter- calated transition metal dichalcogenide CoNb4Se8,Nat. Commun.16, 4399 (2025)

    2025

  21. [21]

    J. Dong, K. Wu, M. Zhu, F. Zheng, X. Li, and J. Zhang, Nonrelativistic spin-splitting multiferroic antiferromag- net and compensated ferrimagnet with zero net magne- tization, arXiv:2501.02914 (2025)

    work page arXiv 2025

  22. [22]

    A. P. Sakhya, M. I. Mondal, M. Sprague, R. B. Regmi, A. K. Kumay, H. Sheokand, I. I. Mazin, N. J. Ghimire, and M. Neupane, Electronic structure of a layered altermagnetic compound CoNb 4Se8, arXiv:2503.16670 (2025)

    work page arXiv 2025

  23. [23]

    Sprague, M

    M. Sprague, M. I. Mondal, A. P. Sakhya, R. B. Regmi, 6 S. Sadhukhan, A. K. Kumay, H. Sheokand, I. I. Mazin, N.J.Ghimire, andM.Neupane, Observationofaltermag- netic spin-splitting in an intercalated transition metal dichalcogenide, arXiv:2508.12985 (2025)

    work page arXiv 2025

  24. [24]

    Janik, E

    E. Janik, E. Dynowska, J. Bąk-Misiuk, M. Leszczyński, W. Szuszkiewicz, T. Wojtowicz, G. Karczewski, A. K. Zakrzewski, and J. Kossut, Structural properties of cubic MnTe layers grown by MBE,Thin Solid Films267, 74– 78 (1995)

    1995

  25. [25]

    M. E. Vickers, D. A. MacLaren, and G. A. Gehring, Elec- trical properties of NiAs-type MnTe films with preferred orientation,J. Appl. Phys.119, 045304 (2016)

    2016

  26. [26]

    Osumi, S

    T. Osumi, S. Souma, T. Aoyama, K. Yamauchi, A. Honma, K. Nakayama, T. Takahashi, K. Ohgushi, and T. Sato, Observation of giant band splitting in altermag- netic MnTe,Phys. Rev. B109, 115102 (2024)

    2024

  27. [27]

    Rößler, V

    S. Rößler, V. Ginga, M. Schmidt, Y. Prots, H. Rosner, U. Burkhardt, U. K. Rößler, and A. A. Tsirlin, Low-field magnetization processes of hexagonal easy-plane alter- magnetα-MnTe, arXiv:2511.01388 (2025)

    work page arXiv 2025

  28. [28]

    R. D. González Betancourt, J. Zubáč, K. Geishendorf, P. Ritzinger, B. Růžičková, T. Kotte, J. Železný, G. Springholz, B. Büchner, A. Thomas, H. Reichlová, D. Kriegner, and T. Jungwirth, Anisotropic magnetoresis- tance in altermagnetic MnTe,Nat. Rev. Phys.6, 683 (2024)

    2024

  29. [29]

    Osumiet al., Observation of giant band splitting in altermagnetic MnTe,Phys

    T. Osumiet al., Observation of giant band splitting in altermagnetic MnTe,Phys. Rev. B109, 115102 (2024)

    2024

  30. [30]

    K. P. Kluczyket al., Coexistence of anomalous Hall effect and weak magnetization in a nominally collinear antifer- romagnet MnTe,Phys. Rev. B110, 155201 (2024)

    2024

  31. [31]

    Watanabe, R

    R. Watanabe, R. Yoshimi, M. Shirai, T. Tanigaki, M. Kawamura, A. Tsukazaki, K. S. Takahashi, R. Arita, M. Kawasaki, and Y. Tokura, Emergence of interfa- cial conduction and ferromagnetism in MnTe/InP,Appl. Phys. Lett.113, 181602 (2018)

    2018

  32. [32]

    Chilcoteet al., Stoichiometry-induced ferromag- netism in altermagnetic candidate MnTe,Adv

    M. Chilcoteet al., Stoichiometry-induced ferromag- netism in altermagnetic candidate MnTe,Adv. Funct. Mater.34, 2405829 (2024)

    2024

  33. [33]

    J. D. Wasscher, Evidence of weak ferromagnetism in MnTe from galvanomagnetic measurements,Solid State Commun.3, 169–171 (1965)

    1965

  34. [34]

    S.Beyet al., UnexpectedtuningoftheanomalousHallef- fect in altermagnetic MnTe thin films, arXiv:2409.04567 (2024)

    work page arXiv 2024

  35. [35]

    S. Bey, M. Zhukovskyi, T. Orlova, S. S. Fields, V. Lauter, H. Ambaye, A. Ievlev, S. P. Bennett, X. Liu, and B. A. Assaf, Interface, bulk and surface structure of heteroepitaxial altermagneticα-MnTe films grown on GaAs(111),Phys. Rev. Mater.9, 074404 (2025)

    2025

  36. [36]

    A.H. Chen, P. R. Raghuvanshi, J. Cook, M. Chilcote, J. Lapano, A. R. Mazza, Q. Lu, S. Kim, Y.-C. Wu, T. Z. Ward, B. J. Lawrie, G. Bian, J. Burns, J. D. Poplawsky, M.-G. Han, Y. Zhu, L. Lindsay, H. Miao, Z. Gai, R. G. Moore, G. Eres, V. R. Cooper, and M. Brahlek, Pro- grammable phase selection between altermagnetic and noncentrosymmetric polymorphs of MnTe...

    2026

  37. [37]

    Bangar, P

    H. Bangar, P. Tsipas, P. Rout, L. Pandey, A. Kal- aboukhov, A. Lintzeris, A. Dimoulas, and S. P. Dash, Interplay between altermagnetic order and crystal sym- metry probed using magnetotransport in epitaxial alter- magnet MnTe, arXiv:2505.14589 (2025)

    work page arXiv 2025

  38. [38]

    S. Li, J. Wu, B. Liang, L. Liu, W. Zhang, N. Wazir, J. Zhou, Y. Liu, Y. Nie, Y. Hao, P. Wang, L. Wang, Y. Shi, and S. Li, Antiferromagneticα-MnTe: Molten- Salt-Assisted Chemical Vapor Deposition Growth and Magneto-Transport Properties,Chem. Mater.34, 873 (2022)

    2022

  39. [39]

    Zhang, Q

    J. Zhang, Q. Lian, Z. Pan, W. Bai, J. Yang, Y. Zhang, X. Tang, and J. Chu, Spin-phonon coupling and two- magnonsscatteringbehaviorsinhexagonalNiAs-typean- tiferromagneticMnTeepitaxialfilms,J Raman Spectrosc. 51, 1383 (2020)

    2020

  40. [40]

    Strauch and B

    D. Strauch and B. Dorner, Phonon dispersion in GaAs, J. Phys.: Condens. Matter2, 1457 (1990)

    1990

  41. [41]

    Kommichau, H

    G. Kommichau, H. Neumann, and W. Schmitz, Thermal expansion of SrF2 at elevated temperatures,Cryst. Res. Technol.21, 1583 (1986)

    1986

  42. [42]

    P. E. Blöchl, Projector augmented-wave method,Phys. Rev. B50, 17953 (1994)

    1994

  43. [43]

    Kresse and J

    G. Kresse and J. Hafner, Ab initio molecular-dynamics simulation of the liquid-metal–amorphous-semiconductor transition in germanium,Phys. Rev. B49, 14251 (1994)

    1994

  44. [44]

    Kresse and J

    G. Kresse and J. Furthmúller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set,Phys. Rev. B54, 11169 (1996)

    1996

  45. [45]

    Kresse and D

    G. Kresse and D. Joubert, From ultrasoft pseudopoten- tials to the projector augmented-wave method,Phys. Rev. B59, 1758 (1999)

    1999

  46. [46]

    J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple,Phys. Rev. Lett. 77, 3865 (1996)

    1996

  47. [47]

    A. I. Liechtenstein, V. I. Anisimov, and J. Zaanen, Density-functional theory and strong interactions: Or- bital ordering in Mott–Hubbard insulators,Phys. Rev. B 52, R5467 (1995)

    1995

  48. [48]

    H. J. Monkhorst and J. D. Pack, Special points for Brillouin-zone integrations,Phys. Rev. B13, 5188 (1976)

    1976

  49. [49]

    A. Togo, L. Chaput, T. Tadano, and I. Tanaka, Imple- mentation strategies in phonopy and phono3py,J. Phys. Condens. Matter35, 353001 (2023)

    2023

  50. [50]

    Togo, First-principles phonon calculations with phonopy and phono3py,J

    A. Togo, First-principles phonon calculations with phonopy and phono3py,J. Phys. Soc. Jpn.92, 012001 (2023)

    2023

  51. [51]

    Momma and F

    K. Momma and F. Izumi, vesta3 for three-dimensional visualization of crystal, volumetric and morphology data, J. Appl. Crystallogr.44, 1272 (2011)

    2011