What are Altermagnets?

Feb. 7, 2024

In a new study, scientists have investigated the newly discovered class of altermagnetic materials for their thermal properties, offering insights into the distinctive nature of altermagnets for spin-caloritronic applications.

About Altermagnets:

Altermagnets exhibit a unique blend of magnetic characteristics, setting them apart from conventional magnetic materials like ferromagnets and antiferromagnets.
Properties:
- These materials exhibit properties observed in both ferromagnets and antiferromagnets, making their study enticing.
- Altermagnets defy conventional norms by embodying a dual nature—resembling antiferromagnets with zero net magnetization and ferromagnets with non-relativistic spin splitting.
- This unique behaviour emerges from the intricate interplay of atoms within the crystal structure.
- Additionally, altermagnets exhibit a unique spin polarisation. The term "spin polarisation" means that a preponderance of electron spins tends to align in a particular direction.
- The spin polarisation is noteworthy in altermagnets because it occurs in the physical arrangement of atoms (real space) and in the momentum space, where the distribution of electron spins in the material is considered.
- The researchers believe that altermagnets could have a pivotal role in spin caloritronics, a field of research that explores the interplay between spin and heat flow, which are not achievable with ferromagnets or antiferromagnets.
- This field has potential applications in developing new technologies for information processing and storage.
The researchers focused on studying the emergence of crystal Nernst and crystal thermal Hall effects in rubidium dioxide (RuO2), chosen as a showcase representative of altermagnetism.
The crystal Nernst effect (CNE) observed in altermagnets is a result of their distinctive magnetic nature.
- In simple terms, as the material experiences a temperature difference across its dimensions, it leads to the emergence of a voltage perpendicular to both the temperature gradient and the magnetic field.
- This phenomenon reveals that the material's magnetic properties influence its response to temperature changes, providing insights into the intricate connection between thermal and magnetic behaviours in altermagnets.