The study, led by Professor Kim Young-keun of Korea University and Professor Nam Ki-tae of Seoul National University, was published in Science on September 4, 2025. Their team successfully made "nanohelices," or spiral-shaped magnetic structures, that filter electron spins based on their handedness, or chirality. This could help build faster, more energy-efficient electronic devices in the future.
Spintronics is a new way to process information using the spin of electrons rather than just their charge. It promises smaller, faster, and less power-hungry data storage and computing. However, one of the main challenges has been finding materials that can easily and reliably control spin direction.
The team discovered that combining shape and magnetism can solve this problem. By making spiral structures out of magnetic materials, they discovered that they could control the direction of spin simply using geometry and the material’s natural magnetism — and it works at room temperature.
"These nanohelices achieve spin polarization exceeding about 80 percent, just by their geometry and magnetism," said Professor Kim. "It is a rare combination of structural chirality and intrinsic ferromagnetism, and it works at room temperature. We do not need complex magnetic circuits or cooling systems."
To build the nanohelices, the researchers used an electrochemical method and added tiny amounts of chiral organic molecules like cinchonine or cinchonidine. These molecules acted like templates that helped the metal form into spirals with either left-handed or right-handed twists. This kind of control is well known in organic chemistry but almost never achieved in metals.
Once the helices were made, the team showed that right-handed ones allowed one spin direction to pass through, while blocking the opposite spin. That makes them function like spin filters. This is the first time this effect has been observed in a 3D inorganic structure.
To prove the handedness of each nanohelix, the researchers invented a test based on electromotive force, or emf. When they rotated a magnetic field around the helices, the left- and right-handed spirals generated opposite emf signals. This lets them measure chirality even in materials that do not react to light.
Because the nanohelices are magnetic, they can also send spin information across long distances — even without being aligned in a specific direction. This effect did not happen in non-magnetic versions of the same helices, showing that magnetism is essential for this behavior.
The team also built a working solid-state device that showed different electrical signals depending on whether it used left- or right-handed helices. This shows that the technology can be used in real electronic devices.
"Chirality is well-known in organic chemistry and biology, where the left or right twist of a molecule can determine how it functions," said Professor Nam. "But controlling chirality in metals is extremely difficult. We achieved it here just by adding a small amount of chiral molecules, which is a major breakthrough in materials chemistry." Professor Kim said, adding: "We believe this system could become a platform for chiral spintronics and help design more advanced magnetic nanostructures."
The team’s technique also allows them to control not just the direction of the twist, but also how many strands the helix has, which could open even more possibilities in future electronics.
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