Why in the News?
Scientists discovered a new type of magnetism called altermagnetism, confirmed in 2024, which combines features of ferromagnetism and antiferromagnetism.
What is Altermagnetism?
- Overview: A new form of magnetism discovered in 2019 and proven experimentally in 2024; combines traits of ferromagnetism and antiferromagnetism.
- Mechanism: Atoms have opposite (antiparallel) spins like in antiferromagnets, but their alignment follows mirror or rotational symmetry, not simple alternation.
- Magnetic Effect: Although it has no external magnetic field, the electrons show different energy levels for spin-up and spin-down states.
- Discovery: First observed in manganese telluride (MnTe) through photoemission and X-ray imaging techniques.
- Scientific Relevance: Introduces a magnetically neutral but electronically active material class useful for next-generation electronics.
Distinctive Properties:
- Zero External Magnetism: Produces no external field but shows strong internal spin asymmetry.
- Spin-Polarised Currents: Can carry magnetic-like electric currents without stray fields.
- Ultrafast Response: Works at terahertz (THz) frequencies, about 1000× faster than conventional magnetic devices.
- Stable Performance: Maintains stable magnetic order even under changing conditions.
- Crystal-Based Symmetry: Magnetism arises from atomic structure, not external alignment.
How does it differ from other Magnetisms?
- Ferromagnetism: All spins align in the same direction, creating a strong external magnetic field.
- Antiferromagnetism: Spins align in opposite directions, fully cancelling magnetism with equal spin energy.
- Altermagnetism: Spins align oppositely but mirror-linked, giving energy difference between spins, no net field, yet internal magnetic effects.
Applications:
- Spintronics: Enables compact, energy-efficient data storage and logic devices.
- Quantum Computing: Provides magnetically quiet materials for stable qubit performance.
- High-Speed Electronics: Supports ultrafast processors operating at terahertz levels.
- Advanced Sensors: Useful for precise, low-noise magnetic detection.
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