New Twisted Polymer Steers Electron Spin Without Magnets, Osaka Team Reports

Researchers at the University of Osaka have created a new class of semiconducting polymers whose molecular structures twist like left- or right-handed spirals and can generate highly spin-polarised electrical currents. Reported in Nature Communications, the polymers self-assemble into helical structures that filter electrons by their spin, which the team presents as a platform for future spintronic devices.

The work draws on chirality, the property by which an object has distinct left- and right-handed forms, seen in corkscrewed vines and spiralling seashells. Conventional electronics rely only on the flow of electrical charge. Spintronics also harnesses electron spin, an intrinsic property that can carry information while using less energy, so controlling it could lead to greener, more efficient technologies. The challenge has been finding materials that reliably generate spin-polarised currents.

Instead of bulky magnetic materials, the team used molecular structure to control spin. Lead author Fumitaka Ishiwari says the approach takes advantage of the flexibility of organic materials. The researchers designed polymers with a rigid bifacial ladder framework, an architecture that encourages the molecules to form highly ordered helices and improves their ability to transmit electrons of a chosen spin orientation.

When built into electronic devices, the currents the polymers produced were highly spin-polarised, and the material also showed high thermal stability. The team frames the result as a step toward spintronic devices and clean-energy technologies that would not depend on magnets, using the twist of the molecule itself to do the work.