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arxiv: 2512.14660 · v2 · submitted 2025-12-16 · ❄️ cond-mat.mes-hall · cond-mat.mtrl-sci

Thermomagnonic Torques in Insulating Altermagnets

Edward Schwartz , Hamed Vakili , Alexey A. Kovalev This is my paper

Pith reviewed 2026-05-16 21:36 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall cond-mat.mtrl-sci
keywords thermomagnonic torquesinsulating altermagnetsspin-splitter torqueentropic torquedomain wall dynamicsskyrmion Hall effecttemperature gradientsmagnon spin splitting
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The pith

Insulating altermagnets produce anisotropic torques from temperature gradients that precess domain walls and direct skyrmions with reduced sideways motion.

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

The paper establishes a symmetry-based theory for thermomagnonic torques in insulating altermagnets. It identifies a spin-splitter magnonic torque arising from thermally generated sublattice-odd spin currents and an anisotropic entropic torque determined by crystal symmetry. These mechanisms cause magnetic textures like domain walls and skyrmions to respond anisotropically to temperature gradients, for instance by precessing domain walls to slow their motion in particular directions and enabling fast skyrmion travel with suppressed Hall deflection in symmetry-allowed orientations. A sympathetic reader would care because the results give concrete, direction-dependent predictions for how heat flows can control magnetism in materials without net magnetization.

Core claim

The authors develop a symmetry-controlled theory identifying a spin-splitter magnonic torque from thermally generated sublattice-odd spin currents and an anisotropic entropic torque dictated by crystal symmetry. These torques produce anisotropic magnetic-texture responses to temperature gradients, including domain-wall precession that reduces velocities for selected directions and an anisotropic skyrmion Hall response with symmetry-selected directions enabling fast motion and strongly suppressed transverse deflection.

What carries the argument

Spin-splitter magnonic torque linked to thermally generated sublattice-odd spin currents, together with the anisotropic entropic torque fixed by crystal symmetry, which together set the direction-dependent torques on magnetic textures.

Load-bearing premise

The magnon spectrum and spin currents can be described accurately using only symmetry arguments in a linear-response regime without a specific microscopic Hamiltonian or checks for higher-order scattering.

What would settle it

Observation of reduced domain-wall velocity along particular crystal directions under a temperature gradient, or direction-dependent variation in skyrmion Hall angle that follows the predicted anisotropy.

Figures

Figures reproduced from arXiv: 2512.14660 by Alexey A. Kovalev, Edward Schwartz, Hamed Vakili.

Figure 1
Figure 1. Figure 1: FIG. 1. A minimal model of a two-sublattice altermagnet. [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Entropic and magnonic spin-splitter torques in an [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (a) The domain wall velocity, (b) the angular preces [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. (a) Components of the skyrmion velocity, [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
read the original abstract

We develop a symmetry-controlled theory of anisotropic thermomagnonic torques in insulating altermagnets. We identify a spin-splitter magnonic torque linked to thermally generated, sublattice-odd spin currents and an anisotropic entropic torque dictated by crystal symmetry. These torques produce anisotropic magnetic-texture responses to temperature gradients. In particular, thermally generated spin currents induce domain-wall precession, which reduces domain-wall velocities for selected gradient directions. We also predict an anisotropic skyrmion Hall response, with symmetry-selected directions enabling fast skyrmion motion with strongly suppressed transverse deflection. Our results reveal experimentally testable symmetry fingerprints of insulating altermagnets and extend more broadly to anisotropic magnets with exchange-driven magnon spin splitting.

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 develops a symmetry-controlled theory of thermomagnonic torques in insulating altermagnets. It identifies a spin-splitter magnonic torque arising from thermally generated sublattice-odd spin currents together with an anisotropic entropic torque fixed by crystal symmetry. These torques are shown to produce direction-dependent responses of magnetic textures to temperature gradients, including domain-wall precession that reduces velocity along selected axes and an anisotropic skyrmion Hall angle that can be suppressed along symmetry-allowed directions.

Significance. If the symmetry arguments and linear-response treatment hold, the work supplies experimentally testable symmetry fingerprints that distinguish insulating altermagnets from conventional antiferromagnets and extends the framework to other exchange-split anisotropic magnets. The predictions for domain-wall dynamics and skyrmion motion under thermal gradients are concrete and could guide magnonic or spintronic experiments once microscopic verification is supplied.

major comments (2)
  1. [Main derivation (symmetry analysis and linear-response section)] The central derivation relies on a symmetry-controlled linear-response treatment of the magnon spectrum and spin currents, yet no explicit microscopic Hamiltonian (e.g., a Heisenberg model with altermagnetic exchange) is provided to confirm that the predicted sublattice-odd currents survive and that higher-order magnon-magnon or magnon-phonon scattering remains negligible for realistic temperature gradients. This assumption is load-bearing for the claimed domain-wall precession and anisotropic skyrmion Hall response.
  2. [Abstract and introductory claims] The abstract and introductory claims present the torques as arising directly from symmetry without accompanying explicit equations, error estimates, or cross-checks against a microscopic model. Consequently the quantitative statements about reduced domain-wall velocities and suppressed transverse skyrmion deflection cannot be verified from the given text.
minor comments (2)
  1. [Notation and definitions] Notation for the spin-splitter torque and entropic torque should be introduced with a clear table or equation list early in the manuscript to aid readability.
  2. [Introduction] A brief comparison paragraph with existing thermomagnonic torque literature in ferromagnets or conventional antiferromagnets would help situate the new altermagnetic contributions.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments on our manuscript. We address each major point below and have revised the manuscript accordingly to strengthen the microscopic foundation and clarify the presentation of our results.

read point-by-point responses

  1. Referee: [Main derivation (symmetry analysis and linear-response section)] The central derivation relies on a symmetry-controlled linear-response treatment of the magnon spectrum and spin currents, yet no explicit microscopic Hamiltonian (e.g., a Heisenberg model with altermagnetic exchange) is provided to confirm that the predicted sublattice-odd currents survive and that higher-order magnon-magnon or magnon-phonon scattering remains negligible for realistic temperature gradients. This assumption is load-bearing for the claimed domain-wall precession and anisotropic skyrmion Hall response.

    Authors: We agree that an explicit microscopic example strengthens the work. In the revised manuscript we have added a dedicated section containing a minimal Heisenberg Hamiltonian with altermagnetic exchange. We explicitly diagonalize the magnon spectrum, compute the thermally generated spin currents, and verify that the sublattice-odd components survive. We also include estimates showing that, for the small temperature gradients considered, the linear-response regime holds and higher-order scattering contributions remain negligible to leading order. revision: yes

  2. Referee: [Abstract and introductory claims] The abstract and introductory claims present the torques as arising directly from symmetry without accompanying explicit equations, error estimates, or cross-checks against a microscopic model. Consequently the quantitative statements about reduced domain-wall velocities and suppressed transverse skyrmion deflection cannot be verified from the given text.

    Authors: The abstract is kept concise by convention, but we have expanded the introduction to include the central linear-response equations for the thermomagnonic torques and the symmetry-allowed spin-current components. We have added error estimates derived from the symmetry constraints and cross-references to the new microscopic-model section, enabling direct verification of the predicted reductions in domain-wall velocity and the suppression of the skyrmion Hall angle along symmetry-selected directions. revision: yes

Circularity Check

0 steps flagged

Symmetry-controlled derivation of thermomagnonic torques is self-contained with no circular reductions

full rationale

The paper develops a symmetry-controlled linear-response theory to identify spin-splitter magnonic torques from sublattice-odd spin currents and anisotropic entropic torques from crystal symmetry. These lead to predictions of domain-wall precession and anisotropic skyrmion Hall response. No equations or steps reduce predictions to fitted inputs by construction, no self-citations bear the central load, and no ansatz or renaming of known results is invoked. The framework is presented as independent of specific microscopic Hamiltonians, with symmetry dictating allowed terms rather than smuggling in results.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claims rest on symmetry arguments for altermagnets and linear magnon transport; no free parameters or new entities are introduced in the abstract.

axioms (2)
  • domain assumption Altermagnetic symmetry allows sublattice-odd spin splitting in the magnon spectrum while preserving zero net magnetization.
    Invoked to link thermal magnon currents to net spin current.
  • standard math Linear response theory applies to thermally generated magnon spin currents under small temperature gradients.
    Used to derive torques without higher-order scattering.

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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. Supercurrent-Driven N\'eel Torque in Superconductor/Altermagnet Hybrids

    cond-mat.mes-hall 2026-03 unverdicted novelty 6.0

    Supercurrents in superconductor/altermagnet hybrids generate a tunable Néel torque that can propel domain walls and reverse Néel vector orientation.

Reference graph

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