Research/Sitter/Altermagnetics / INDEX.md

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Altermagnetics corpus — assembled 2026-08-20

61 open-access PDFs, arXiv identifiers preserved in the filename. Grouped by the question each answers. A second list at the bottom holds DOIs that are paywalled and need fetching by hand.

Filename convention: <arXiv-id>_<theme>_<slug>.pdf. Themes: switching, gate, filter, origin, tj (tunnel junctions), mat (materials), sim, tool, vcma, review, inductance. A paper with no arXiv identifier carries its DOI with / written as -, or a short source name.

Start here

• 2508.09748_review_altermagnetic-spintronics.pdf — the large multi-institution review. Framing.
• 2607.12320_sim_minimal-4x4-QAH-dwave-model.pdf — the whole minimal model in four equations.
• 2604.15454_sim_mumaxplus-altermagnets.pdf — the micromagnetic implementation, and the source of the claim that altermagnetic textures do carry stray fields.

Q1/Q7 — what sets and switches the Néel vector, and at what cost

• 2412.17013 electrical manipulation of spin-splitting torque in RuO2
• 2412.20938 electrical switching of altermagnetism
• 2510.11362 deterministic switching via asymmetric sublattice spin current
• 2603.06537 deterministic electrical switching via surface antisymmetry groups
• 2508.13585 Néel switching via magnetic multipole torque
• 2604.04203 ultrafast Néel vector switching (femtosecond, ~5 orders faster than torque switching)
• 2512.23397 THz switching by Néel spin-orbit torques
• 2604.00325 WFeB — electrically switchable perpendicular spin-splitter response
• 2605.10747 theory of spin-splitter magnetoresistance

Low-voltage write, from the MTJ side:

• 2511.18143 interface-engineered voltage-driven MTJ, ultra-low-energy switching
• 1705.05092 ultrafast low-energy switching, voltage-controlled elliptical pMTJ
• 2202.01156 antiferromagnetic parametric resonance driven by VCMA

Reference numbers: VCMA write energy has reached 6 fJ (Ta-CoFeB-MgO, TMR 45%); the historical bottleneck was ~100 fJ/bit and >2 V write. In antiferromagnets, VCMA parametric pumping is reported 1–2 orders more efficient than microwave or spin-orbit-torque excitation.

Q2 — turning regions on and off; multistate and analog retention

This is the ferroelectric/multiferroic route, and it is the strongest answer in the corpus.

• 2411.14216_gate_ferroelectric-switchable-altermagnetism.pdf — reversing ferroelectric polarization reverses the altermagnetic spin splitting. 22 ferroelectric altermagnets identified by screening 2001 experimental magnetic structures in MAGNDATA; two are ferroelectric switchable.
• 2512.10405_switching_efield-controlled-altermagnetic-transition-neuromorphic.pdf — ultra-low-power electric-field control, framed for neuromorphic computing.
• 2505.20843 ferroelastic altermagnetism · 2510.14193 ferroelasticity-tunable altermagnets
• 2606.11862 ferroelectric altermagnetic Chern insulator, electrical control of Chern number
• 2508.12770 chiral altermagnetic magnetoelectrics
• 2504.03179 magnetic-field-tuned randomness in inhomogeneous altermagnets
• 2607.15728 giant multistate resistance switching, CrSb multiferroic tunnel junctions
• 2503.13850 above-room-temperature multiferroic tunnel junction with CrSb

Mechanism: the applied field acts on crystal deformation modes — rotations of the sublattice units — and those rotations are what generate the altermagnetism in the first place. So the gate does not merely bias the magnet, it reaches the symmetry that creates the spin splitting, and can flip its sign.

Q3 — origin of the splitting

• 2604.18337 direct observation of quadruple spin-texture locking in a 2D d-wave altermagnet
• 2510.02452 spin polarization engineering in d-wave altermagnets
• 2602.13590 ARPES, symmetry, non-relativistic band splitting
• 2410.00909 altermagnetism from interaction-driven itinerant magnetism
• 2607.17997 stripe-order altermagnetism · 2602.10641 antiferroaxial altermagnetism
• 2606.31573 high-harmonic spin-current signatures of spin-group symmetry

Q4 — directional filtering, the "funnel"

The closest thing in the literature to what you described, and it is real.

• 2604.20312_filter_perfect-spin-nonreciprocity-transverse-momentum.pdf — explicitly a selective filter of transverse momentum channels
• 2606.04587_filter_lifshitz-open-orbit-spintronics.pdf — open-orbit spintronics via a homotopic Lifshitz transition; directional transport by Fermi-surface topology
• 2602.21460 intrinsic spin filter in KV2Se2O with an open Fermi surface
• 2605.13317 interface-controlled spin filtering, altermagnet/Ising-superconductor
• 2607.00506 atom-selective spin-polarized transport in a charge-ordered altermagnet
• 2607.13923 angular-momentum splitter, d-wave axial phonons
• 2606.21545 mirror-symmetry-enforced photonic altermagnet

Q5/Q6 — orientation engineering, tunnel junctions, arrays

• 2607.21092 TMR with Cr-doped RuO2(110) · 2604.14776 spin-valley-mismatched giant TMR
• 2605.12711 negative differential resistance + ultra-high TMR
• 2607.03908 2D altermagnetism by surface functionalization, giant TMR
• 2608.13265 topological superconductors in doubly-coupled nanowires

Array-level context is not in this corpus (it is conventional memory-architecture literature). The two coupled obstacles for 3D cross-point are sneak-path leakage and uniform multilayer process integration; the standard answer is a 1S1R cell with a two-terminal bidirectional threshold-switching selector in series with each junction.

Materials

2607.21803 MnTe single crystals · 2608.17513 MnTe film growth · 2608.09371 MnTe magnetotransport · 2508.19969 MnTe doping / quasi-altermagnetism · 2608.08741 CrSb thin films · 2607.07334 CrSb spin-polarized transport · 2607.29646 CrSb anomalous Hall · 2603.03694 NiF2 XMCD · 2607.15197 FeSe monolayer · 2606.26023 RuO2 under epitaxial strain · 2405.10820 RuO2 absence of magnetic order

Tools

2401.08784 amcheck · 2604.21397 FINDSPINGROUP · 2511.21821 IRSSG · 2411.18194 mumax+ · 2608.15253 Claude-SpinDynamics · 2604.15985 ML/DL for quantum materials

Paywalled — need fetching by hand

Added by hand, 2026-08-21 — ../Spintronics/

Fetched from paywalled sources; staged in the sibling Spintronics/ directory.

The two that matter most

2410.06071v3.pdf — Antiferroelectric Altermagnets. = Phys. Rev. Lett. 134, 106801 (2025). Duan/Zhang/Zhu/Liu/Zhang/Zutic/Zhou (EIT Ningbo + Buffalo + USTC). Does NOT screen MAGNDATA — it proposes the mechanism and validates on two hand-picked materials, CuWP2S6 and BiCrO3. Duan, Zhang, Zhu, Liu, Zhang, Zutic, Zhou. This is the pseudo-gate, as material physics.

A new multiferroic class, AFEAM, where antiferroelectricity and altermagnetism coexist in one material. The design principle: two antiferromagnetic sublattices connected by a rotation give an altermagnet with spin polarization Ps != 0; connected by a translation they give a conventional AFM with Ps = 0. An electric field switches the material between the two. So the field does not bias the magnet — it changes which symmetry relates the sublattices, and the spin splitting turns off. Their words: "even a weak electric field can effectively toggle spin polarization in the AFEAM by switching between antiferroelectric and ferroelectric states." Validated by first principles in vdW metal thio(seleno)phosphates and perovskite oxides, 2D monolayer through 3D bulk.

h13n-whcx.pdf — Giant TMR driven by momentum-selective resonant tunneling in double-barrier altermagnetic tunnel junctions. Zou, Zhang, Gao, Phys. Rev. B 114, 084405 (2026), DOI 10.1103/h13n-whcx. This is the directional filter, computed.

Structure RuO2/TiO2/RuO2/TiO2/RuO2 (001) — two barriers with an altermagnetic quantum-well spacer between them. DFT (VASP, GGA+U, Ueff 2.3 eV Ru 4d / 5.0 eV Ti 3d) plus NEGF in QuantumATK, 401x401 k-mesh. TMR up to 75,094% against 200-500% for the single-barrier junction.

The mechanism is the part to read. Because the spin splitting is k-dependent, the resonance condition E_r(k_par) = E_F is met at different k_par for each spin channel, producing "localized transmission hot spots near the Brillouin-zone corners". Parallel configuration puts QW states on the Fermi level and transmission approaches unity; reversing the Neel vector destroys the resonance across the whole zone. Control knobs are QW thickness and barrier thickness — geometry sets which transverse momenta transmit.

Note the authors' own caveat: RuO2's magnetic ground state is under active debate and they adopt the altermagnetic RuO2 model because it is the one used in the comparable first-principles literature. The material may not survive. The mechanism is not RuO2-specific.

Also in Spintronics/

• 2411.14216v2.pdf — Ferroelectric switchable altermagnetism, v2 (corpus has v1)
• Physics.18.58.pdf — "Altermagnets That Turn On and Off". APS Physics viewpoint, a commentary on PRL 134 106801/106802, not primary literature. Useful as an explainer, not as a citation.
• s41467-023-41826-1.pdf — Ballistic transport spectroscopy of spin-orbit-coupled bands in monolayer graphene on WSe2. Nat. Commun. 14, 6124 (2023). Transverse magnetic focusing, Veselago lensing, Fabry-Perot interference, ballistic snake states; SOC ~13 meV. Electron optics — steering ballistic carriers geometrically, which is the complement to filtering them by momentum.
• Adv Materials Inter 2023 Garcia-Ruiz — flat bands for electrons in rhombohedral graphene multilayers with a twin. Correlated flat-band physics.

Why these three fit together

The architecture needs three things and there is now a paper for each: a gate that turns the splitting on and off (AFEAM, by electric field), a filter that admits only chosen transverse momenta (double-barrier QW resonance, by geometry), and steering of ballistic carriers (transverse magnetic focusing and Veselago lensing). Gate, filter, funnel.

Correction, and the census that was actually run

The 2001-structure MAGNDATA screen belongs to the companion paper, not to AFEAM. Two different groups, published back to back in the same PRL issue, which is why one APS viewpoint covers both.

PRL134-106802_screening_ferroelectric-switchable-altermagnetism.pdf = arXiv:2411.14216 = Phys. Rev. Lett. 134, 106802 (2025). Gu, Liu, Zhu, Yananose, Chen, Hu, Stroppa (CNR-SPIN L'Aquila), Qihang Liu (SUSTech Shenzhen, corresponding). PRL Collection of the Year 2025.

Method, reproducible. They diagnosed spin space groups for all 2001 MAGNDATA structures using their own public online tool FINDSPINGROUP (findspingroup.com; paper in this corpus as 2604.21397). Qihang Liu's group also authored the underlying SSG theory, PRX 12 021016 and PRX 14 031038 — theory, tool, and census all from one group.

Filter, two rules:

1. spin splitting requires joint PT and T·tau (tau a fractional lattice translation) to be broken
2. ferroelectricity requires the spatial part of the parent space group to be polar

Then for switchable: find SSG operations mapping P -> -P and S -> -S simultaneously, and check the path is reachable by field alone without reversing the Neel vector.

Result: 22 ferroelectric altermagnets, 2 switchable — Ca3Mn2O7 (Cmc21) and Cr-MOF [C(NH2)3]Cr(HCOO)3 (Pna21). Cr-MOF: 3 eV gap, ~20 meV VBM splitting, DFT GMR ~53% on a 184-atom supercell. Switching path is decisive: reversing the X1- mode costs ~4 eV/cell and does NOT flip the splitting; reversing the X4+ mode (a Q2 Jahn-Teller distortion) costs ~0.1 eV and does. Ca3Mn2O7 has the larger splitting at ~100 meV.

On "why only 2001": they say they searched "all the MAGNDATA database", and MAGNDATA reached 2000 entries in Nov 2022, so it was a census rather than a sample. Two caveats worth checking: growth from 2000 (2022) to 2001 (2024) is implausibly flat for a database open to submissions, and their citation [20] is the commensurate MAGNDATA paper (Gallego, J. Appl. Cryst. 49, 1750), so the incommensurate set may be excluded without saying so.

The gap: rule (ii) selects for ferroelectric. Nobody has run this census for antiferroelectric altermagnets — AFEAM proposed that mechanism and screened nothing. Same database, same public tool, inverted polarity condition, unsearched space.

Still blocked

Coil inductance — added 2026-10-10

The inductance of a winding of any shape: the conductor's own path, its cross-section, its partner windings and the permeable bodies around it. 42 PDFs, theme inductance (and tool for solver manuals).

Thin wire on any curve

• 1204.1486 Dengler — self-inductance of a wire loop as a curve integral; the general thin-wire form
• 1804.11098 O'Hara — regularization of self-inductance
• 2310.09313 Hurwitz, Landreman, Antonsen — self field, force and inductance of coils, round section
• 2310.12087 Landreman et al. — the same, rectangular section
• 2105.12522 McGreivy et al. — Biot–Savart with straight segments at higher-order convergence
• 2009.00196 McGreivy et al. — finite-build coils
• 1903.10207 Poletkin — mutual inductance of arbitrarily oriented circular filaments
• 10.6028-jres.001.018 Snow 1928 — mutual inductance of any two circles
• Cavaliere 2021 (skew straight filaments, Campbell's formula as Grover gives it) is in the hand-fetch list below

Classical formulas and their oracles (NBS, free)

• 10.6028-bulletin.034 Rosa 1906 — self-inductance of single-layer coils (round-wire corrections)
• 10.6028-bulletin.088 Rosa 1908 — self and mutual inductances of linear conductors (partial inductance, GMD)
• 10.6028-bulletin.185 Rosa & Grover 1912 — formulas and tables
• 10.6028-bulletin.348 Grover 1919 — additions to the formulas
• 10.6028-nbsscipaper.141 Grover 1922 — coils of polygonal form (square, triangle, polygons)
• 10.6028-nbsscipaper.212 Snow 1926 — inductance of a helix of any wire section; the helix gold standard
• 10.6028-jres.009.029 Snow 1932 — helix formula with lead-in corrections
• 10.6028-jres.069c.016 Hoer & Love 1965 — exact inductance of rectangular conductors
• knight-2012 Knight — supplement and errata to Grover's Inductance Calculations
• hamwaves Stroobandt — single-layer helical coil calculator notes (Knight's formulas)

Finite cross-section, PEEC and planar spirals

• 10.1109-4.792620 Mohan et al. 1999 — planar spiral expressions (empirical fit, sanity check only)
• 10.7716-aem.v8i4.1074 Aebischer 2019 — square spirals with rectangular section; FastHenry2 references and measured PCB coils
• atlantis-25848342 — multilayer FR-4 rectangular coil against HFSS
• isqed-3C.2-028 — multi-layer, multi-shape PCB coil design flow
• mezhiba-friedman-2002 — loop and partial inductance of on-chip current loops
• paul-emc-newsletter-2010 Paul — comment on Ruehli's partial-inductance paper
• torchio-thesis Torchio — unstructured PEEC extended to magnetic materials
• 10.23919-ROPACES.2018.8364275 VoxHenry — FFT-accelerated inductance extraction on voxels
• yucel-ntu-c40 VoxCap — the capacitance counterpart
• 10.21105-joss.06644 pyPEEC — voxel PEEC solver (MPL-2.0)
• fasthenry — FastHenry 3.0 user guide and non-uniform ground-plane manual

Scale, coupling to bodies, eddy currents

• 2210.16609 Börm & Henningsen — H²-matrices for translation-invariant kernels
• 1805.10358 Binysh & Alexander — Maxwell's solid angle; the line-integral form used for a coil's scalar potential
• 1806.01390 Ilott & Jerschow — reciprocity, and its use in conductive media
• 2008.10886 Liu et al. — coils inside cuboid shields; the method of images for permeable walls
• 2509.15528 Shah — image of a magnetic dipole before a superconducting sphere
• 2301.11249 Deidda et al. — EM induction over a multilayered conducting half-space (Dodd–Deeds kernel)
• woodson-melcher-ch2 Woodson & Melcher — lumped electromechanical elements, speed voltage
• 10.1137-130932132 Trefethen & Weideman — the exponentially convergent trapezoidal rule

Winding representation

• 2605.31009 Denis et al. — explicit turns with anisotropic homogenisation
• degreve-cefc2010 De Grève, Dular et al. — frequency-domain homogenization of wire bundles
• 2506.14085 Takahashi et al. — shape optimisation of mutual inductances among coils
• 1109.4881 Clem — geometry-dependent critical currents (current crowding at corners)

To fetch by hand — paywalled or blocked to scripts