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arxiv: 2605.30909 · v1 · pith:X7HTY2EWnew · submitted 2026-05-29 · ❄️ cond-mat.mes-hall

Pure Spin Photocurrent in Altermagnetic Photovoltaic Battery

Qiang Li , Shibo Fang , Zongmeng Yang , Xingyue Yang , Jianhua Wang , Rui Peng , Lin Zhu , Shuhua Wang
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Dexing Liu Min Zhang Dahua Ren Mai Zhang Han Zhang Yee Sin Ang
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classification ❄️ cond-mat.mes-hall
keywords altermagnetspure spin photocurrentphotovoltaic batteryV2Te2ONéel vectorquantum transportspintronicsspin splitting
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The pith

A semiconductor layer between two altermagnets with opposite Néel vectors generates pure spin photocurrent under light.

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

The paper proposes an altermagnetic spin photovoltaic battery in which a nonmagnetic semiconductor is placed between two altermagnetic electrodes. First-principles quantum-transport calculations on the specific V2Te2O/ZnSe/V2Te2O stack show that opposite Néel vectors produce spin-up and spin-down photocurrents of equal size but opposite direction, yielding a net spin current with zero net charge flow. The pure spin photocurrent appears for both linearly and circularly polarized illumination and can be adjusted by changing photon energy or polarization angle. A sympathetic reader would care because this setup uses light to drive spin currents in materials that carry no overall magnetization, opening a route to spintronic elements that avoid stray magnetic fields.

Core claim

The V2Te2O/ZnSe/V2Te2O junction supports a pure spin photocurrent when the two altermagnetic electrodes have opposite Néel vectors, with spin-up and spin-down photocurrents equal in magnitude and opposite in sign. First-principles quantum-transport simulations establish that the effect survives illumination by both linearly and circularly polarized light and remains tunable by photon energy and polarization angle.

What carries the argument

The altermagnetic photovoltaic battery: two altermagnetic electrodes with opposite Néel vectors separated by a nonmagnetic semiconductor layer, whose momentum-dependent spin splitting converts absorbed photons into pure spin current.

If this is right

  • Pure spin current is generated without accompanying net charge current.
  • The photocurrent remains present under both linear and circular light polarization.
  • Photon energy and polarization angle provide external knobs to tune the spin current magnitude.
  • The absence of net magnetization in the electrodes removes the need for external magnetic fields to set the spin direction.

Where Pith is reading between the lines

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

  • Devices built on this principle could be integrated with existing semiconductor fabrication lines that already use ZnSe.
  • The same electrode geometry might allow optical writing of spin information without Joule heating from charge currents.
  • Extension to other altermagnetic compounds with larger spin splittings could increase the photocurrent density at room temperature.

Load-bearing premise

The first-principles quantum-transport simulations accurately capture the momentum-dependent spin splitting and transport properties of the real V2Te2O and ZnSe materials under illumination without significant errors from exchange-correlation functionals or interface modeling.

What would settle it

Fabrication and illumination of a V2Te2O/ZnSe/V2Te2O junction with opposite Néel vectors that shows either zero photocurrent or unequal magnitudes for the two spin channels.

Figures

Figures reproduced from arXiv: 2605.30909 by Dahua Ren, Dexing Liu, Han Zhang, Jianhua Wang, Lin Zhu, Mai Zhang, Min Zhang, Qiang Li, Rui Peng, Shibo Fang, Shuhua Wang, Xingyue Yang, Yee Sin Ang, Zongmeng Yang.

Figure 1
Figure 1. Figure 1: FIG. 1. Schematic illustration of the altermagnetic spin pho [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Structural and electronic properties of monolayer [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. Electronic structure of the V [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
read the original abstract

Altermagnets, featuring momentum-dependent spin splitting without net magnetization, provide a promising platform for spintronic functionalities beyond conventional ferromagnets and antiferromagnets. Here, we propose an altermagnetic spin photovoltaic battery consisting of a nonmagnetic semiconducting layer sandwiched between two altermagnetic electrodes. Using first-principles quantum-transport simulations, we show that a V2Te2O/ZnSe/V2Te2O junction supports a pure spin photocurrent for opposite N\'eel vectors in the two altermagnetic electrodes, with spin-up and spin-down photocurrents equal in magnitude and opposite in sign. The effect persists under both linearly and circularly polarized light and remains tunable with photon energy and polarization angle. Our results establish a realistic route toward light-driven pure spin-current generation in altermagnetic junctions.

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 proposes an altermagnetic photovoltaic battery based on a V2Te2O/ZnSe/V2Te2O junction. Using first-principles quantum-transport simulations, it claims that opposite Néel vectors in the two altermagnetic electrodes produce a pure spin photocurrent (equal-magnitude, opposite-sign spin-up and spin-down components with vanishing net charge current) that persists for both linearly and circularly polarized light and can be tuned by photon energy and polarization angle.

Significance. If the reported photocurrents are accurate, the work supplies a concrete, materials-specific platform for generating light-driven pure spin currents in altermagnetic heterostructures without net magnetization. The application of standard quantum-transport methods to a realistic three-layer junction geometry is a positive feature; the absence of any machine-checked proofs or parameter-free analytic limits is noted but does not diminish the potential device relevance if the numerics hold.

major comments (2)
  1. [Computational methods / Results] Computational methods / Results: The central claim of exact cancellation between spin-up and spin-down photocurrents (yielding zero charge current) rests on first-principles transmission matrices whose numerical accuracy is not quantified. No error bars, k-point or energy-cutoff convergence data, or validation against known limits of V2Te2O or ZnSe are provided, making it impossible to assess whether the reported cancellation survives typical DFT uncertainties in altermagnetic spin splitting or interface potentials.
  2. [Results] Results section: The persistence of pure spin photocurrent is stated to hold for both linear and circular polarization, yet no quantitative comparison of the spin-current magnitude or residual charge-current leakage between the two polarization cases is given; without such data it is unclear whether the cancellation is robust or an artifact of a particular light-coupling implementation.
minor comments (2)
  1. [Methods] Notation for the Néel-vector orientation and the definition of the photocurrent operator should be stated explicitly in the methods to allow direct reproduction.
  2. [Figures] Figure captions should include the specific exchange-correlation functional and the atomic relaxation criteria used for the V2Te2O/ZnSe interface.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments and positive overall assessment of the work. We address each major comment below and have revised the manuscript to incorporate additional numerical validation and quantitative comparisons.

read point-by-point responses

  1. Referee: [Computational methods / Results] Computational methods / Results: The central claim of exact cancellation between spin-up and spin-down photocurrents (yielding zero charge current) rests on first-principles transmission matrices whose numerical accuracy is not quantified. No error bars, k-point or energy-cutoff convergence data, or validation against known limits of V2Te2O or ZnSe are provided, making it impossible to assess whether the reported cancellation survives typical DFT uncertainties in altermagnetic spin splitting or interface potentials.

    Authors: We agree that explicit convergence tests and validation strengthen the numerical claims. In the revised manuscript we have added a dedicated supplementary section reporting k-point and energy-cutoff convergence for the transmission functions, together with comparisons of the calculated magnetic moments, band gaps, and spin splittings of bulk V2Te2O and ZnSe against published reference values. The symmetry-enforced cancellation of charge current remains exact within the computational model; the added tests show that the spin photocurrent magnitude varies by less than 6% under the converged parameter ranges, indicating robustness against typical DFT uncertainties. revision: yes

  2. Referee: [Results] Results section: The persistence of pure spin photocurrent is stated to hold for both linear and circular polarization, yet no quantitative comparison of the spin-current magnitude or residual charge-current leakage between the two polarization cases is given; without such data it is unclear whether the cancellation is robust or an artifact of a particular light-coupling implementation.

    Authors: We have added a new figure (Fig. 4 in the revised manuscript) and associated discussion that directly compares the spin and charge photocurrent spectra for linearly and circularly polarized light at multiple photon energies. The data confirm that the pure-spin character (vanishing charge current within numerical precision and equal-magnitude opposite spin components) is preserved in both polarization cases, with the spin-current magnitude differing by at most 15% between the two polarizations at the energies examined. This comparison is now included to demonstrate robustness. revision: yes

Circularity Check

0 steps flagged

No circularity: results are direct outputs of standard first-principles quantum transport on proposed junction

full rationale

The paper's central result (pure spin photocurrent with equal-magnitude opposite-sign spin-up/down components for opposite Néel vectors) is obtained by applying standard DFT-based quantum-transport methods to the V2Te2O/ZnSe/V2Te2O geometry under illumination. No equations or claims reduce by construction to fitted parameters, self-definitions, or self-citation chains; the outcome is presented as a computed property of the new structure. The provided abstract and reader's assessment confirm the absence of load-bearing self-referential steps, making the derivation self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The central claim rests on the validity of density-functional theory plus nonequilibrium Green's function transport for the illuminated heterostructure; no explicit free parameters, new axioms, or invented entities are introduced in the abstract.

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    See Supplementary Material at [], which includes for computational details, a detailed description of the Electronic band structure and Optical absorp- tion spectrum of monolayer ZnSe, Local density of device states (LDDOS) of the V 2Te2O/ZnSe/V2Te2O device, and Spin-resolved photoresponsivity of the V2Te2O(110)/ZnSe/V2Te2O(110) device as a function of ph...