Multipole analysis of spin currents in altermagnetic MnTe
Pith reviewed 2026-05-18 14:39 UTC · model grok-4.3
The pith
In altermagnetic MnTe the combination of intrinsic spin-orbit coupling and altermagnetic spin splitting produces a magnetic spin Hall angle reaching 16 percent.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Using multipole symmetry analysis together with relativistic Kubo transport calculations, the authors establish that in α-MnTe the choice of Néel-vector direction (N̂ ∥ y versus N̂ ∥ x) selects different order parameters; these in turn generate spin-momentum locking of opposite parities and magnetic spin Hall effects whose anisotropies differ, with the largest magnetic spin Hall angle reaching 16 percent when intrinsic spin-orbit coupling acts together with the altermagnetic spin splitting.
What carries the argument
The multipole framework that classifies the distinct order parameters arising from different Néel-vector orientations and links them to the resulting spin currents and magnetic spin Hall conductivities.
If this is right
- Néel-vector orientation directly controls both the magnitude and the anisotropy of the magnetic spin Hall effect in MnTe.
- The magnetic spin Hall angle of 16 percent makes MnTe competitive with heavy metals for efficient spin-current generation at zero net magnetization.
- Measuring the anisotropy of the magnetic spin Hall effect provides an experimental handle to identify which order parameter is realized.
- The multipole classification supplies a systematic way to predict spin-transport properties across other altermagnets.
Where Pith is reading between the lines
- Device architectures could exploit the predicted anisotropy to electrically detect or switch between different altermagnetic states.
- Similar large magnetic spin Hall angles may appear in other altermagnets once their multipole order parameters are mapped.
- The same symmetry-plus-Kubo workflow can be applied to predict spin currents in altermagnetic heterostructures or under strain.
Load-bearing premise
The first-principles Kubo calculations correctly capture the altermagnetic spin splitting and the spin-orbit-driven transport without large errors from the exchange-correlation functional or finite-size approximations.
What would settle it
Experimental measurement of the magnetic spin Hall angle in oriented MnTe films that yields a value well below or far above 16 percent for the predicted Néel-vector orientations would falsify the calculated magnitude.
Figures
read the original abstract
Altermagnets, a class of unconventional antiferromagnets where antiparallel spins are connected by combined rotational and translational symmetries, have recently emerged as promising candidates for spintronic applications, as they can efficiently generate spin currents while maintaining vanishing net magnetization. Here, we investigate charge transport and spin currents in $\alpha$-MnTe, a prototypical altermagnet, using symmetry analysis within the multipole framework and fully relativistic first-principles calculations using the Kubo formalism. Our results show that different magnetic configurations with N\'eel vectors $\hat{N}\parallel y$ and $\hat{N}\parallel x$ in MnTe induce distinct order parameters. This distinction gives rise to spin-momentum locking with different parities and magnetic spin Hall effects (magnetic SHEs) with different anisotropies. Strikingly, our calculations show that the combination of intrinsic spin-orbit coupling and altermagnetic spin splitting yields a large magnetic spin Hall angle of up to 16 \% rivaling or exceeding that of heavy metals such as Pt. On the other hand, the anisotropy of the magnetic SHE provides a practical means to identify the type of order parameter. This establishes, through the powerful framework of multipoles, a general approach for studying transport phenomena that extends to a broader class of altermagnets beyond MnTe.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript applies multipole symmetry analysis and fully relativistic first-principles Kubo-formula calculations to charge and spin transport in the altermagnet α-MnTe. It shows that Néel vectors along x versus y produce distinct magnetic order parameters, different-parity spin-momentum locking, and anisotropic magnetic spin Hall effects, with the combination of intrinsic SOC and altermagnetic splitting yielding a magnetic spin Hall angle reaching 16 %.
Significance. If the numerical results are robust, the work demonstrates that altermagnets can generate large spin currents without net magnetization and with efficiencies comparable to or exceeding those of heavy metals such as Pt. The multipole framework supplies a general, symmetry-based route to classify and predict such transport phenomena across the wider family of altermagnets.
major comments (1)
- Computational methodology section: The headline result is a magnetic spin Hall angle of up to 16 % obtained from the fully relativistic Kubo linear-response formula. No convergence data are reported for k-mesh density or the broadening parameter η. Because the altermagnetic spin splittings are only tens of meV, both parameters can shift the conductivity by tens of percent when the mesh fails to resolve Fermi-surface features or when η is comparable to the splitting; this directly affects the quantitative claim that the angle rivals Pt.
minor comments (2)
- Abstract: The maximum value of 16 % should be tied explicitly to a particular Néel-vector orientation or current direction so that the anisotropy statement can be checked against the later figures.
- Figure captions: Several panels lack explicit labels for the Néel-vector direction or the spin-current component being plotted, making it difficult to connect the plots directly to the multipole order parameters discussed in the text.
Simulated Author's Rebuttal
We thank the referee for the careful reading of our manuscript and for the constructive comment regarding the computational methodology. We address the point below and will revise the manuscript to incorporate additional convergence information.
read point-by-point responses
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Referee: Computational methodology section: The headline result is a magnetic spin Hall angle of up to 16 % obtained from the fully relativistic Kubo linear-response formula. No convergence data are reported for k-mesh density or the broadening parameter η. Because the altermagnetic spin splittings are only tens of meV, both parameters can shift the conductivity by tens of percent when the mesh fails to resolve Fermi-surface features or when η is comparable to the splitting; this directly affects the quantitative claim that the angle rivals Pt.
Authors: We agree that explicit convergence tests are important to substantiate the quantitative value of the magnetic spin Hall angle, especially given the scale of the altermagnetic splittings. In the revised manuscript we will expand the Computational Methodology section with a new paragraph (or subsection) presenting convergence data for both the k-mesh density and the broadening parameter η. These tests confirm that the reported spin Hall angle remains stable to within a few percent once the k-mesh exceeds the density used in the main calculations and for η values well below the altermagnetic splitting. This addition will directly address the referee’s concern and strengthen the reliability of the 16 % figure. revision: yes
Circularity Check
No significant circularity; results from independent first-principles Kubo + multipole symmetry analysis
full rationale
The paper computes the magnetic spin Hall angle (up to 16%) via fully relativistic DFT and the Kubo linear-response formula applied to the electronic structure of α-MnTe, combined with symmetry analysis in the multipole framework. These steps rely on external computational codes and standard first-principles methodology rather than fitting parameters to the target observable or reducing via self-citation chains. No equation or claim in the abstract or described methodology reduces the reported value to an input by construction; the derivation remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (2)
- domain assumption Fully relativistic first-principles calculations within the Kubo formalism accurately describe spin currents in the presence of altermagnetic order.
- domain assumption Multipole symmetry analysis correctly classifies the distinct order parameters for Néel vectors along x versus y.
Reference graph
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Symmetry-imposed shape of response tensors Table VII summarizes the response tensor forms, for both ˆN∥yand ˆN∥x, as derived from the active mul- tipoles. We note that the dissipative and magnetic REE vanish inα-MnTe, which is a direct consequence of the in- version symmetry of the crystal. The dissipative EC and intrinsic SHE exhibit the same multipole d...
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Dissipative electric conduction and intrinsic spin Hall effect For the dissipative EC and intrinsic SHE shown in Fig. 7 and Fig. 8, the trends are similar to those of the AHE and magnetic SHE; hole doping produces a much stronger response than electron doping. Note that the intrinsic SHE of MnTe has six independent components of the SHC tensor, in contras...
discussion (0)
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