Textbook update due? Altermagnetism emerges as new class of magnetic order, PgII.

Key Highlights:

• Altermagnetism, a new class of magnetic order, has emerged, differing from ferromagnetism and antiferromagnetism.
• First formulated around 2019 and supported by experiments in 2024, altermagnetism is garnering interest for use in spintronics and quantum technologies.
• Altermagnets have no net external magnetic field, making them less susceptible to external disturbances.
• Studies published on November 6 proposed new ways to probe the hidden magnetic structure of altermagnets using circularly polarised X-rays.

Detailed Insights:

• Altermagnetism combines properties of both ferromagnets and antiferromagnets, behaving like antiferromagnets externally but possessing an internal electronic structure similar to ferromagnets.
• The unique atomic arrangement in altermagnets, involving rotations or mirror-flips, results in zero net magnetisation while enabling spin-splitting, where electrons with different spins move at slightly different rates.
• Angle-resolved photoemission spectroscopy (ARPES) and X-ray magnetic dichroism are used to study altermagnets, as traditional magnetometers are ineffective due to the absence of an external magnetic field.
• Spintronics could benefit from altermagnets due to their potential for faster, smaller, and more energy-efficient memory and logic devices, as well as their ability to carry spin-polarised currents.
• Challenges remain in synthesising high-quality, single-domain altermagnetic materials and developing scalable fabrication techniques for commercial applications.
• Materials like manganese telluride (MnTe) and ruthenium dioxide (RuO2) have been central in demonstrating altermagnetic effects.
• The anomalous Hall effect in some altermagnets allows for electrical reading of the material’s magnetic state, offering an advantage for device integration.

Key Concepts Involved:

• Ferromagnetism: A type of magnetism where small magnetic moments align in parallel, creating a strong external magnetic field.
• Antiferromagnetism: A type of magnetism where alternating magnetic moments cancel each other out, resulting in no net external magnetic field.
• Spintronics: A technology that uses electron spin as well as charge to store and process information.
• Anomalous Hall effect: The production of a sideways voltage in a material when an electric current flows through it.