For years, controlling magnetism in electronic devices has been a significant challenge. The conventional approaches require large magnetic fields or substantial electrical power, which often results in bulky systems that are slow, expensive, and waste a lot of energy. But the landscape of magnetism in electronics may be on the verge of a revolutionary change, thanks to the discovery of a new class of materials known as altermagnets. These materials are providing new ways to manage magnetism efficiently, opening up exciting possibilities for spintronics and other technologies.
Altermagnets represent a new frontier in the study of magnetism, offering a unique blend of properties that were previously thought to be incompatible. By unlocking the potential of these materials, scientists are working on the next generation of devices that could change how we think about electronics, memory storage, and even computing.
Traditional Magnetism: Ferromagnetism and Antiferromagnetism
Before diving into the details of altermagnets, it’s important to understand the traditional forms of magnetism that have been the foundation of our knowledge. Ferromagnetism and antiferromagnetism are the two well-established types of magnetic orderings in materials.
- Ferromagnetism (FM): This is the type of magnetism we’re most familiar with, as seen in common objects like refrigerator magnets or compass needles. In ferromagnetic materials, the magnetic moments of atoms align in parallel within a crystal structure, creating a strong overall magnetic field. This alignment is stable, even without an external magnetic field.
- Antiferromagnetism (AFM): This form of magnetism was discovered around a century ago. In antiferromagnetic materials, the magnetic moments of atoms align in alternating directions within a crystal structure. While the individual atoms or ions have magnetic moments, they cancel each other out due to this alternating alignment. As a result, the material does not exhibit a net macroscopic magnetization. Antiferromagnetic behavior is often observed at low temperatures.
These two types of magnetism have formed the core of our understanding of magnetic materials for decades. However, they were limited in their applications. While ferromagnets were great for creating strong and stable magnetic fields, antiferromagnets, despite their potential in specific scenarios, lacked the necessary characteristics for widespread use in technology.
The Emergence of Altermagnets
In early 2022, physicists introduced the concept of a third type of magnetism—altermagnetism—which has properties of both ferromagnetism and antiferromagnetism, yet is fundamentally distinct. Altermagnets have attracted significant attention for their unique behavior and their potential to pave the way for more efficient, faster, and energy-conserving technologies.
What sets altermagnets apart from traditional magnetic materials is their behavior under the influence of crystal symmetry and spin alignment. In an altermagnet, the magnetic moments in the crystal alternate in a way that results in no net magnetization, similar to antiferromagnetism. However, unlike antiferromagnets, altermagnets do not have simple cancellation of their magnetic moments. Instead, their crystal symmetry induces an electronic band structure that exhibits strong spin-dependent effects, allowing the spins to flip in different directions as you move deeper through the material’s energy bands.
This unique behavior means that altermagnets have the potential to combine the best properties of ferromagnets and antiferromagnets. They do not have a net magnetization in their ground state, but they can still exhibit strong spin-dependent effects. These properties make altermagnets an excellent candidate for use in spintronics, a field where the spin of electrons is used to process and store information, much like how the charge of electrons is used in conventional electronics.
Spintronic devices that rely on altermagnets could potentially be more energy-efficient, faster, and have higher storage capacities than traditional electronic devices, unlocking a wealth of possibilities for next-generation computing.
The Search for Efficient Switching of Altermagnets
One of the major hurdles in practical applications of altermagnets lies in controlling and switching their magnetic properties. In traditional spintronics, this is done using external magnetic fields or electric currents, but these methods often require bulky systems that consume a lot of power and are not ideal for fast switching.
In 2023, a significant breakthrough was made when researchers led by Tong Zhou at the Eastern Institute of Technology in Ningbo, China, developed a switch that could control the magnetism in altermagnets with unprecedented efficiency. Zhou’s team introduced a simple yet elegant way of managing altermagnetism using electric fields—a much more practical and energy-efficient method compared to the traditional magnetic fields.
Zhou explained the concept in simple terms: “We’ve created a material that lets you control magnetism as easily as turning the handle on your faucet. Imagine having two knobs: when they’re set opposite each other, you get a special magnetic current; when they’re turned the same way, it turns off. It’s that simple.”
The proposed device works by using the electric field to polarize the spin states of the altermagnet, switching the material between different spin configurations. In this way, an altermagnet could act as an efficient magnetic switch in spintronic devices, significantly reducing the energy consumption and physical size of magnetic components.
The Antiferroelectric-Altermagnet: A New Concept
A key development in this research was the idea of an antiferroelectric altermagnet (AFEAM), which combines the properties of both antiferroelectric materials and altermagnets. Antiferroelectric materials are those where the electric dipoles are aligned in opposite directions within the material. Zhou’s group hypothesized that these materials could be coupled with the magnetic spins in a way that allows the electric field to switch between ferroelectric and antiferromagnetic states.
This concept was further elaborated in their proposal. A small electric field applied to an antiferroelectric altermagnet would cause the dipoles to align in the same direction, transforming the material from an altermagnet to a ferroelectric state. In this state, the material would behave like an antiferromagnet, where the magnetic moments are no longer aligned, thus disabling its ability to polarize an electronic current.
This innovation of toggling between different magnetic and electric states with an electric field creates an extremely efficient switch that could be used in future devices like memory storage, sensors, and computing components. The ability to switch magnetism on and off in such a controlled, energy-efficient way has the potential to revolutionize how electronic devices operate.
Further Developments and Proposals
In addition to Zhou’s groundbreaking work, other researchers are exploring similar ideas for electric-field-controlled magnetic switching. A research group led by Qihang Liu at the Southern University of Science and Technology in Shenzhen, China, and independent researcher Libor Šmejkal at the Max Planck Institute for the Physics of Complex Systems in Germany, are also investigating ferroelectric switchable altermagnets. These materials could use applied electric fields to interact with the deformation modes of the crystal structure, such as the Jahn-Teller distortion (an alternating contraction and elongation of bonds) or sublattice rotations.
Both these proposals aim to use electric fields to reverse the ferroelectric polarization in the material, thus enabling control over the sign of the altermagnet’s spin splitting. The concept of altermagnetoelectric effects (where the electric field influences the magnetism) opens up new avenues for creating faster, more energy-efficient devices that integrate both magnetic and electric functionalities.
A Game-Changer for Spintronics
The discovery and ongoing development of altermagnets with the ability to be controlled by electric fields could be a game-changer for spintronics and other applications in material science. The merging of antiferroelectricity and altermagnetism is a novel and promising concept that could bring about a new class of smart materials with low-energy, high-speed switching capabilities.
The ability to manipulate magnetism so efficiently and at such small scales will not only revolutionize existing technologies but also open up new applications that were previously considered impractical. As Zhou stated, “It feels like we’ve uncovered a hidden switch inside materials—one that lets us toggle spin behavior without ever touching the magnetic structure. That’s a game-changer.”
Conclusion: A New Era of Efficient Devices
As research into altermagnets progresses, we are getting closer to the day when we can manipulate magnetism with the ease of turning a switch. This breakthrough has the potential to make devices faster, more energy-efficient, and smaller, while reducing their environmental impact. From memory storage to quantum computing, altermagnets could play a central role in the next generation of electronic devices.
By moving away from traditional methods of controlling magnetism and harnessing the power of electric fields, altermagnets represent a major leap forward in materials science. The future of electronics could be driven by the ability to efficiently manage spin, opening up exciting possibilities for both practical applications and new theoretical discoveries.
Reference: Xunkai Duan et al, Antiferroelectric Altermagnets: Antiferroelectricity Alters Magnets, Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.106801. On arXiv: DOI: 10.48550/arxiv.2410.06071