Scientists unveil new way to electrically control spin for ultra-compact devices using altermagnetic quantum materials

Spintronics, an emerging field of technology, exploits the spin of electrons rather than their charge to process and store information. Spintronics could lead to faster, more power-efficient computers and memory devices. However, most spintronic systems require magnetic fields to control spin, which is challenging in ultracompact device integration due to unwanted interference between components. This new research provides a way to overcome this limitation.

As published in Materials Horizons, a research team led by the Singapore University of Technology and Design (SUTD) has introduced a novel method to control electron spin using only an electric field. This could pave the way for the future development of ultra-compact, energy-efficient spintronic devices.

Their findings demonstrate how an emerging type of magnetic material, an altermagnetic bilayer, can host a novel mechanism called layer-spin locking, thus enabling all-electrical manipulation of spin currents at room temperature.

What is altermagnetism?

Altermagnetism is a unique type of magnetism where materials exhibit an unusual property: the spins of electrons in the material point in opposite directions, creating a balance of magnetic moments that cancels out any large-scale magnetization. This phenomenon is distinct from traditional ferromagnetism and antiferromagnetism, as it leads to the ability to create non-collinear spin currents and unique electronic behavior that can be finely tuned. This makes altermagnetic materials ideal for applications in spintronics, where precise control over spin states is needed.

The team discovered that in an altermagnetic bilayer—a system composed of two ultra-thin layers of the material chromium sulfide (CrS)—electrons naturally separate into layers with opposite spin directions. By applying a simple electric field, the researchers found that they could completely switch the spin polarization, achieving a sign-reversible spin polarization of up to 87% at room temperature.

“We show that spin can be controlled purely by an electric field, eliminating the need for magnetic fields. This paves the way for ultra-compact, highly efficient spintronic devices,” said lead author Dr. Rui Peng from SUTD.

How it works: A new pathway for spin control

In the bilayer system, the researchers observed a unique effect that they call layer-spin locking. Unlike conventional magnetic materials where spin-polarized currents are influenced by external magnetic fields, the bilayer structure allows each layer to carry an opposite spin-polarized current. When an electric field is applied, it selectively lifts the energy levels of one layer over the other, resulting in a strong, tunable spin-polarized current.

“Imagine having two conveyor belts carrying electrons with opposite spins,” explained SUTD Assistant Professor Yee Sin Ang, who led the research team. “With a simple voltage switch, we can make one conveyor belt dominate over the other, flipping the spin of the transported electrons. This is the essence of our work.”

Next steps and real-world applications

This discovery has major implications for next-generation computing, memory storage, and quantum technologies. The researchers envision that their work could inspire new materials and device designs based on altermagnetic materials.

The next phase of this research will focus on experimental validation and device prototyping. The team is exploring ways to integrate its bilayer system into real-world circuits and demonstrate its feasibility in commercial spintronic applications.

“The ultimate goal is to develop practical, manufacturable spintronic devices that can outperform today’s silicon-based electronics,” Assistant Professor Ang added. “This study provides the blueprint for how we can get there.”

As the race to develop next-generation computing accelerates, all-electrical spintronics is set to play a pivotal role. This study represents a significant step forward, proving that, with the right material engineering, the future of ultra-fast, energy-efficient computing could be closer than we think.

This research was conducted collaboratively by SUTD, Hong Kong University of Science and Technology, Beijing Institute of Technology, Zhejiang University and A*STAR Singapore.