Altermagnetism : Discovery
The discovery of altermagnetism represents a step forward in physicists’ understanding of the magnetic world.
- Magnetism has long been categorised into two primary types: ferromagnetism and antiferromagnetism.
- Ferromagnetism is responsible for the behaviour of materials like iron and nickel, where all magnetic moments align in the same direction, producing strong magnetisation – such as the force that makes fridge magnets stick.
- Antiferromagnetism occurs when magnetic moments align in a regular pattern but point in opposite directions, cancelling each other out and resulting in no external magnetic field.
- Altermagnetism is a type of magnetism where magnetic moments (tiny magnetic fields created by electrons) align in opposite directions but follow a distinct rotated pattern.
- This unique arrangement creates properties that combine key elements of both ferromagnets and antiferromagnets.
- Like antiferromagnets, altermagnets have magnetic moments that align in opposite directions, cancelling out any overall magnetisation.
- However, like ferromagnets, altermagnets still allow spin-polarised currents. In ferromagnets, spin-polarised currents can only occur because all electron spins or moments align in one direction (producing a magnetic field).
- The key distinction in altermagnets is that the larger, crystal-like structures holding these magnetic moments are rotated relative to each other, creating distinct electronic behaviours.
- It is the rotation of these larger structures that allows for spin-polarised currents to still occur in altermagnets.
- This makes altermagnets potentially valuable for a variety of applications, particularly in electronics and data storage.
- They eliminate the possibility of stray magnetic fields while still allowing for a spin-polarised current – a highly useful combination for modern electronics.
