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Altermagnetism, a newly proposed magnetic phase

Idea Proposed

Image

a, Unit cell of α-MnTe with Mn spins collinear to the magnetic easy axis. Applying transforms the left unit cell into the right. The unit cells with opposite L vector produce the same XMLD but inequivalent XMCD owing to-symmetry breaking in altermagnetic MnTe. b, Illustration of the vector mapping process. The colour wheels show the angular dependence of the XMCD, three-colour XMLD and six-colour vector map on the in-plane vector direction. The XMCD acts on the three-colour XMLD, with light XMCD regions changing the colour and dark XMCD regions leaving it unchanged to produce the six-colour L-vector map. In the XMLD and vector map, coloured segments indicate the magnetic easy axes oriented along the crystallographic directions. c–e, XMCD-PEEM (c), XMLD-PEEM (d) and vector map (e) of a 25-μm2 region of unpatterned MnTe film. f, An expanded view of the boxed region in e in which a vortex–antivortex pair is identified. The vortex–antivortex core positions are highlighted by the magenta–white and cyan–white circles, respectively. The combination of XMLD-PEEM and XMCD-PEEM imaging allows for unambiguous determination of the helicity of the swirling textures of the altermagnetic order vector, indicated by the six colours and overlaid vector plot. Scale bars, 1 μm (c) and 250 nm (f). g, X-ray absorption spectrum (XAS), plotted in black, and XMCD spectrum, plotted in red, measured across the Mn L2,3 resonant edges. The XMCD spectrum is scaled by ×50. a.u., arbitrary units.



Altermagnetism, a newly proposed magnetic phase that combines key features of both ferromagnets and antiferromagnets.

How Altermagnetism Works

This method uses X-ray magnetic circular dichroism (XMCD) and X-ray magnetic linear dichroism (XMLD) with photoemission electron microscopy (PEEM) to image and control nanoscale spin configurations in MnTe.

  • Altermagnetic Order Mapping: The method maps the spin order at the nanoscale (100 nm) and up to microscale (10 µm).
  • Patterning and Field Cooling: Microstructured MnTe films are thermally cycled in magnetic fields to impose custom spin configurations, including vortices and single-domain states.
  • Spin Polarization Detection: XMCD reveals time-reversal symmetry breaking, distinguishing altermagnets from antiferromagnets.
  • Scalability: The method demonstrates that spintronic devices based on altermagnetism can be highly scalable, energy-efficient, and resistant to external field disturbances.

How We Can Use It

  1. Spintronic Devices: Can be used in memory and logic devices with low energy consumption.
  2. Neuromorphic Computing: Altermagnetic textures like vortices and domain walls can be used for brain-inspired AI chips.
  3. Superconductor Integration: Because they lack net magnetization, altermagnets can be integrated into superconducting circuits.
  4. High-Speed Electronics: Altermagnets allow ultrafast spin switching, improving data storage and computing speeds.

This method paves the way for new quantum materials, next-gen computing, and energy-efficient electronics.

Sources & citation

Amin, O.J., Dal Din, A., Golias, E. et al. Nanoscale imaging and control of altermagnetism in MnTe. Nature 636, 348–353 (2024). https://doi.org/10.1038/s41586-024-08234-x