Antiferromagnetism

Antiferromagnetism is magnetic order in which neighboring moments align oppositely, often canceling the material’s net magnetization while preserving long-range order.

Exchange interaction: A quantum-mechanical interaction that favors particular relative orientations of magnetic moments. Its sign and strength determine whether neighboring moments align antiparallel.
Magnetic moment: A vector measure of the magnetic strength and orientation of a particle or object. The ordered units in an antiferromagnet are magnetic moments.
Ferromagnetism: Magnetic order in which moments align predominantly in the same direction, producing net magnetization. It contrasts with the antiparallel alignment and near-cancellation of antiferromagnets.
Antiferromagnetic spintronics: A technology area that uses antiferromagnetic order to encode or manipulate information. It seeks devices that exploit compensated moments and rapid magnetic dynamics.
Nickel oxide: An inorganic compound, NiO, with a rock-salt crystal structure and antiferromagnetic order below its Néel temperature. NiO is a classic material for studying antiferromagnetic domains and exchange bias.
Néel temperature: The temperature above which an antiferromagnet loses long-range magnetic order. Thermal agitation overcomes the ordered state at this characteristic threshold.
Spin (physics): An intrinsic quantum angular momentum carried by elementary particles and many atomic systems. Atomic spin commonly supplies the moments that form antiferromagnetic order.
Ferrimagnetism: Magnetic order with oppositely aligned moments of unequal magnitude, leaving net magnetization. Unequal opposing moments distinguish ferrimagnets from ideally compensated antiferromagnets.
Exchange bias: A shift in a ferromagnet’s magnetic hysteresis loop caused by coupling to an antiferromagnet. Antiferromagnetic layers can pin neighboring ferromagnetic layers in magnetic devices.
Chromium: A chemical element whose metallic form develops an incommensurate spin-density-wave antiferromagnetic state. Its modulated order demonstrates that antiferromagnetism need not be a simple two-sublattice pattern.

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