(Left) A conventional structure that runs a current through the outside of a magnet to generate spins and drive them into the magnet. Some of the spins leak out as they travel, and this spin loss reduces the efficiency of reorienting the magnet.(Right) The new method proposed in this study is designed to flow current directly into the magnetic material, causing spin to escape in one direction. The spin that escapes acts on the magnetic material as if it were coming in from the opposite direction, creating a self-reorienting effect. The greater the amount of spin lost, the greater the force exerted on the magnet, making it easier to change the magnetization. Credit: Korea Institute of Science and Technology (KIST)
A research team has developed 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 work is in the journal Nature Communications.
Spintronics is a technology that utilizes the "spin" property of electrons to store and control information, and it is being recognized as a key foundation for next-generation information processing technologies such as ultra-low-power memory, neuromorphic chips, and computational devices for stochastic computation, as it consumes less power and is more nonvolatile than conventional semiconductors.
This research is significant because it presents a new approach that can significantly improve the efficiency of these spintronics devices.
Dr. Dong-Soo Han's research team at the Korea Institute of Science and Technology (KIST) Semiconductor Technology Research Center, in collaboration with the research teams of Prof. Jung-Il Hong at DGIST and Prof. Kyung-Hwan Kim at Yonsei University has 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.
Structure illustrating the new principle of self-reversing magnetization direction through spin loss when a current is applied inside a magnetic material. When current flows, spin is generated inside the magnetic material, and some spin escapes in the direction of the antiferromagnet on the right. Normally, this escape of spin is considered a "loss," but in this study, this loss creates the same effect as spin entering the magnetic material, which is what drives the magnetization to reverse itself. In particular, as shown in the figure, the more spin that is lost, the easier the magnetization switch occurs. In other words, it becomes easier to change the magnetization. Credit: Korea Institute of Science and Technology (KIST)
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.
In their experiments, the team demonstrated the paradox that the greater the spin loss, the less power is required to switch magnetization. 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.
A structure that describes a new principle by which a magnetic material can self-switch its magnetization direction through spin loss when a current is passed through it. When current flows, spins are generated inside the magnetic material, and some spins escape in the direction of the antiferromagnet on the right. Normally, this spin escape is considered a 'loss', but in this study, this loss creates the same effect as the spin entering the magnetic material, and becomes the driving force to reverse the magnetization by itself. As shown in the figure on the left, when a pulsed current is applied to the inside of the magnet, some of the spin generated inside the magnet is 'lost' to the adjacent antiferromagnet, reversing the direction of magnetization within the magnet. The direction of the magnetization reversal is dependent on the direction of the applied current pulse. Credit: Korea Institute of Science and Technology (KIST)
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."
More information: Won-Young Choi et al, Magnetization switching driven by magnonic spin dissipation, Nature Communications (2025).
Journal information: Nature Communications
