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arxiv: 2605.27543 · v2 · pith:QFWGIMAKnew · submitted 2026-05-26 · ❄️ cond-mat.mtrl-sci

Atomic-Scale Observation of Symmetry Breaking in Altermagnetic MnTe

Guodong Ren , Jonathan M. DeStefano , Xiao-Wei Zhang , Arashdeep S. Thind , Rajiv Giridharagopal , Jose Angel Castellanos-Reyes , Paul M. Zeiger , Noah Kamm
show 15 more authors
Sijie Xu Zhaoyu Liu Yaofeng Xie Filip Krizek Jan Michalicka Richard Campion Pengcheng Dai Peter Wadley David S. Ginger Tomas Jungwirth Robert F. Klie Jan Rusz Di Xiao Jiun-Haw Chu Juan Carlos Idrobo
This is my paper

Pith reviewed 2026-06-29 16:29 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords altermagnetismMnTeinversion symmetry breakingpolar distortionsSTEMEMCDspin splittingmultiferroic
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The pith

Atomic-scale distortions in MnTe break inversion symmetry and mix altermagnetic spin orders.

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

The paper uses atomic-resolution STEM imaging paired with EMCD to show that MnTe contains widespread polar distortions that break inversion symmetry. These distortions lower the spin-space-group symmetry from the ideal P63/mmc g-wave case, allowing d-wave altermagnetic components and, in lower-symmetry areas, s-wave spin splitting with net magnetization. A sympathetic reader would care because this demonstrates that local lattice structure can tune the form of spin splitting in compensated magnets, which are of interest for scalable spintronics. The work connects ferroelectric-like features directly to the magnetic order at the atomic scale.

Core claim

MnTe is not an ideal uniform P63/mmc g-wave altermagnet at the atomic scale. Instead, it hosts ubiquitous inversion-symmetry-breaking distortions that lower the spin-space-group (SSG) symmetry, admits d-wave altermagnetic components, and in lower-symmetry regimes, even allow s-wave spin splitting (net magnetization). The coexistence of ferroelectric signatures and altermagnetic order establishes local lattice symmetry in MnTe as a control knob for altermagnetic spin splitting, spin current generation, and multiferroic memory applications.

What carries the argument

Atomic resolution STEM imaging combined with EMCD measurements that directly correlate local polar distortions with changes to altermagnetic order and symmetry.

If this is right

  • Local lattice symmetry controls the type of altermagnetic spin splitting.
  • The material admits d-wave altermagnetic components in addition to g-wave.
  • Lower-symmetry regions support s-wave spin splitting with net magnetization.
  • Coexistence of the orders enables control over spin current generation and multiferroic memory functions.

Where Pith is reading between the lines

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

  • Bulk-averaged measurements on MnTe may miss the local symmetry lowering and its effects on spin properties.
  • The same local-probe approach could reveal comparable hidden distortions in other candidate altermagnets.

Load-bearing premise

The EMCD signals at atomic resolution directly reflect the local altermagnetic order and its modification by the observed polar distortions without significant contributions from thickness variations, multiple scattering, or beam-induced effects.

What would settle it

An atomic-scale EMCD map across MnTe showing only uniform g-wave order with no polar distortions or evidence of d-wave or s-wave components would falsify the claim of ubiquitous symmetry breaking.

read the original abstract

The recent discovery of altermagnetism has sparked growing interest in compensated magnetic systems as promising platforms for highly scalable spintronics. Altermagnetism is a distinct magnetic order where opposite spin sublattices are connected by rotation, yielding zero net magnetization but momentum-dependent spin splitting. To date, experimental verification of altermagnetic order has been achieved predominantly through bulk-sensitive techniques, including spin-dependent electronic spectra and transport responses. However, direct atomic-scale evidence that explicitly correlates crystal symmetry, local structural distortions, and magnetic ordering has remained unexplored. Here, we report the direct atomic-scale observation of coexisting polar distortions and altermagnetic order in MnTe, combining atomic resolution scanning transmission electron microscopy (STEM) imaging with electron magnetic chiral dichroism (EMCD) measurements. We reveal that MnTe is not an ideal uniform P63/mmc g-wave altermagnet at the atomic scale. Instead, it hosts ubiquitous inversion-symmetry-breaking distortions that lower the spin-space-group (SSG) symmetry, admits d-wave altermagnetic components, and in lower-symmetry regimes, even allow s-wave spin splitting (net magnetization). The coexistence of ferroelectric signatures and altermagnetic order establishes local lattice symmetry in MnTe as a control knob for altermagnetic spin splitting, spin current generation, and multiferroic memory applications.

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 atomic-resolution STEM imaging combined with EMCD measurements on MnTe, claiming that the material is not an ideal uniform P6_3/mmc g-wave altermagnet at the atomic scale. Instead, it hosts ubiquitous inversion-symmetry-breaking polar distortions that lower the spin-space-group symmetry, admit d-wave altermagnetic components, and in lower-symmetry regions allow s-wave spin splitting with net magnetization. The work positions the coexistence of these ferroelectric signatures and altermagnetic order as a local control knob for spin splitting and multiferroic applications.

Significance. If the central interpretation holds, the result supplies the first direct atomic-scale experimental link between local lattice distortions and modifications to altermagnetic spin-space-group symmetry in MnTe. This would strengthen the case for lattice symmetry as a tunable parameter in altermagnetic spintronics and open routes to multiferroic memory concepts. The combined STEM-EMCD approach is a methodological strength for spatially resolved probing, provided the magnetic contrast is cleanly isolated.

major comments (2)
  1. [Results / EMCD analysis] The central claim that measured atomic-resolution EMCD contrast directly encodes local altermagnetic order modified by the observed polar distortions (abstract and results) rests on the assumption that thickness variations, dynamical scattering, and beam-induced effects contribute negligibly. Without explicit thickness maps, multislice simulations, or control measurements on non-altermagnetic reference regions, apparent local deviations from ideal g-wave order could arise from non-magnetic diffraction contrast rather than intrinsic symmetry lowering.
  2. [Discussion / symmetry analysis] The interpretation that polar distortions lower the SSG symmetry to admit d-wave components and, in some regimes, s-wave spin splitting (abstract) requires quantitative mapping of the local symmetry reduction to the observed EMCD angular dependence. The manuscript does not appear to provide a direct comparison of experimental EMCD patterns against simulated patterns for the reported distorted structures versus the ideal P6_3/mmc case.
minor comments (2)
  1. [Introduction / theory background] Clarify the precise definition of the spin-space-group symmetry lowering (e.g., which rotation or mirror operations are broken) and how it quantitatively maps onto the allowed altermagnetic multipoles.
  2. [Methods / data analysis] Include error bars or statistical measures on the reported EMCD contrast values and distortion amplitudes to allow assessment of the significance of the local variations.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for the constructive comments, which help strengthen the presentation of our results. We address each major comment below.

read point-by-point responses

  1. Referee: [Results / EMCD analysis] The central claim that measured atomic-resolution EMCD contrast directly encodes local altermagnetic order modified by the observed polar distortions (abstract and results) rests on the assumption that thickness variations, dynamical scattering, and beam-induced effects contribute negligibly. Without explicit thickness maps, multislice simulations, or control measurements on non-altermagnetic reference regions, apparent local deviations from ideal g-wave order could arise from non-magnetic diffraction contrast rather than intrinsic symmetry lowering.

    Authors: We thank the referee for this important methodological point. The original manuscript presented the atomic-scale correlation between the simultaneously acquired HAADF-STEM images of polar distortions and the EMCD contrast as evidence for an intrinsic effect, with consistency observed across multiple independent sample regions. To directly address the concern, the revised manuscript will incorporate (i) local thickness maps obtained from low-loss EELS spectra recorded in the same areas, (ii) multislice dynamical simulations of the EMCD signal that incorporate the experimentally measured atomic positions and thicknesses, and (iii) control EMCD measurements performed on a non-altermagnetic reference compound under identical experimental conditions. These additions will allow explicit exclusion of non-magnetic diffraction contributions. revision: yes

  2. Referee: [Discussion / symmetry analysis] The interpretation that polar distortions lower the SSG symmetry to admit d-wave components and, in some regimes, s-wave spin splitting (abstract) requires quantitative mapping of the local symmetry reduction to the observed EMCD angular dependence. The manuscript does not appear to provide a direct comparison of experimental EMCD patterns against simulated patterns for the reported distorted structures versus the ideal P6_3/mmc case.

    Authors: We agree that a quantitative comparison between experiment and simulation for the distorted versus ideal structures would strengthen the symmetry analysis. In the revised manuscript we will add multislice simulations of the EMCD angular dependence calculated for both the ideal P6_3/mmc g-wave structure and the locally distorted atomic configurations extracted from the experimental STEM images. Direct overlay of these simulated patterns with the measured EMCD data will provide the requested quantitative mapping of how the observed inversion-symmetry-breaking distortions modify the allowed altermagnetic components. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental observation paper with self-contained data claims

full rationale

This is an experimental paper reporting atomic-resolution STEM imaging and EMCD measurements on MnTe. The central claims rest on direct observation of polar distortions and magnetic contrast rather than any derivation, equation, or fitted parameter that reduces to its own inputs. No self-definitional steps, fitted predictions, or load-bearing self-citation chains appear in the reported results. External citations to altermagnetism theory are independent of the present measurements and do not create circularity within this work.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The claim rests on the assumption that EMCD at atomic resolution faithfully reports local magnetic symmetry without artifacts and that the observed atomic displacements are intrinsic rather than preparation-induced; no free parameters or new entities are introduced in the abstract.

axioms (2)
  • domain assumption Standard interpretation of EMCD contrast as spin-dependent scattering from local magnetic moments holds at the atomic scale in this material.
    Invoked when linking EMCD measurements to altermagnetic order and its modification by distortions.
  • domain assumption STEM image contrast directly maps atomic column positions without significant delocalization or channeling effects that would obscure inversion-symmetry breaking.
    Required to conclude that the distortions are ubiquitous and lower the SSG symmetry.

pith-pipeline@v0.9.1-grok · 5878 in / 1530 out tokens · 39096 ms · 2026-06-29T16:29:04.692636+00:00 · methodology

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Ferroelectric Altermagnetic Chern Insulator in magnetic field: electrical control of the Chern number

    cond-mat.mes-hall 2026-06 unverdicted novelty 5.0

    A minimal 2D d-wave altermagnetic model with band inversion realizes a ferroelectrically tunable Chern insulator with spontaneous spin canting, enabling C = ±1 and ±2 phases via Berry-curvature reorganization.

Reference graph

Works this paper leans on

1 extracted references · 1 canonical work pages · cited by 1 Pith paper

  1. [1]

    Mencos, A

    1 Šmejkal, L., Sinova, J. & Jungwirth, T. Beyond conventional ferromagnetism and antiferromagnetism: A phase with nonrelativistic spin and crystal rotation symmetry. Physical Review X 12, 031042 (2022). 2 Šmejkal, L., Sinova, J. & Jungwirth, T. Emerging research landscape of altermagnetism. Physical Review X 12, 040501 (2022). 3 Fender, S. S., Gonzalez, O...

    work page arXiv 2022