A recent study by teams from the Korea Institute of Science and Technology (KIST), DGIST, Yonsei University, Seoul National University, University of Kashmir, Kunsan National University and Johannes Gutenberg University Mainz presented a device principle that can utilize "spin loss," which was previously thought of as a simple loss, as a new power source for magnetic control. The team's discovery could offer a new approach to significantly improving the efficiency of spintronics devices.
The team identified a new physical phenomenon that allows magnetic materials to spontaneously switch their internal magnetization direction without external stimuli. Magnetic materials are key to the next generation of information processing devices that store information or perform computations by changing the direction of their internal magnetization. For example, if the magnetization direction is upward, it is recognized as '1', and if it is downward, it is recognized as '0', and data can be stored or computed. Traditionally, to reverse the direction of magnetization, a large current is applied to force the spin of electrons into the magnet. However, this process results in spin loss, where some of the spin does not reach the magnet and is dissipated, which has been considered a major source of power waste and poor efficiency.
Researchers have focused on material design and process improvements to reduce spin loss. But now, the team has found that spin loss actually has the opposite effect, altering magnetization. This means that spin loss induces a spontaneous magnetization switch within the magnetic material, just as the balloon moves as a reaction to the wind being taken out of it.
The new approach exploits magnon dissipation for magnetization control, rather than mitigating it. By combining a single ferromagnetic metal with an antiferromagnetic insulator that breaks symmetry in spin transport across the layers while preserving the symmetry in charge transport, the team realized considerable spin-orbit torques comparable to those found in non-magnetic metals, enough for magnetization switching.
In their experiments, the scientists demonstrated the paradox that the greater the spin loss, the less power is required to switch magnetization. Testing proved that these findings are a result of magnonic spin dissipation, rather than external spin sources.
As a result, the energy efficiency is up to three times higher than conventional methods, and it can be realized without special materials or complex device structures, making it highly practical and industrially scalable.
In addition, the technology adopts a simple device structure that is compatible with existing semiconductor processes, making it highly feasible for mass production, and it is also advantageous for miniaturization and high integration. This enables applications in various fields such as AI semiconductors, ultra-low power memory, neuromorphic computing, and probability-based computing devices. In particular, the development of high-efficiency computing devices for AI and edge computing is expected to be in full swing.
"Until now, the field of spintronics has focused only on reducing spin losses, but we have presented a new direction by using the losses as energy to induce magnetization switching," said Dr. Dong-Soo Han, a senior researcher at KIST. "We plan to actively develop ultra-small and low-power AI semiconductor devices, as they can serve as the basis for ultra-low-power computing technologies that are essential in the AI era."