Kouji Taniguchi carefully adjusted the electrodes in his Tokyo lab, watching as a faint current pulsed through a flake of molybdenum disulfide no wider than a human hair. Inside that seemingly ordinary semiconductor, something extraordinary was happening: chiral molecules were slipping between atomic layers like pages in a book, transforming the material’s fundamental electronic behavior. For the first time, researchers at the Institute of Science Tokyo have demonstrated a way to switch chirality—nature’s left- and right-handedness—on and off at will in a nonchiral material, opening a path toward magnetic-free spintronics.
This breakthrough matters because modern electronics are hitting a wall. As transistors shrink toward atomic scales, heat and energy consumption threaten to stall progress. Spintronics, which harnesses the quantum spin of electrons rather than just their charge, offers a promising alternative. But until now, generating spin-polarized currents required bulky magnets or external magnetic fields—constraints that limit miniaturization and efficiency. The Tokyo team’s method bypasses this entirely by using chirality, a geometric property that can filter electrons by spin through the chirality-induced spin selectivity (CISS) effect.
The researchers focused on MoS₂, a layered van der Waals material with natural gaps between its atomic sheets. Using electrochemical intercalation, they inserted enantiopure chiral molecular cations—specifically, (R)- and (S)-1-(1-naphthyl)ethylamine—into these interlayer spaces. When the chiral molecules were inserted, the material exhibited a strong CISS effect, producing spin currents with orientation matching the 'handedness' of the molecules. When the molecules were removed via deintercalation, the effect vanished. The process was fully reversible and repeatable without damaging the crystal structure, a critical step toward practical device integration.
What surprised the team most was that the chiral molecules didn’t just act as surface filters—they induced a chiral electronic state throughout the bulk of the semiconductor. This means the entire material temporarily becomes chiral, even though it isn’t by nature. As Professor Taniguchi explains, “Because the method developed in this study enables electrochemically reversible control of the insertion and extraction of chiral molecules, it becomes possible to switch the generation of spin-polarized currents on and off through chirality at will.”
Published in ACS Nano in 2026, this work lays the foundation for a new class of spintronic devices that are faster, more energy-efficient, and free from magnetic components. The implications stretch from ultra-low-power computing to novel memory technologies. While commercial applications are still on the horizon, the ability to write and erase chirality like data on a hard drive signals a shift in how we think about controlling quantum properties in solids. In a world hungry for sustainable tech, this tiny semiconductor flake in a Tokyo lab may just be pointing the way forward.