Currents Control Spiral Spin Structures
In so-called spintronic devices, which have applications in communications and computing, information is encoded in patterns formed by electron spins. For efficient device operation, these spin patterns typically need to be manipulated using electric currents. Such electrical control has been demonstrated for certain spin patterns but not for helix-shaped ones, which have potentially useful features including chirality and collective dynamics. Now Je-Geun Park at Seoul National University, South Korea, and his colleagues have achieved electrical control of helical spin patterns and uncovered the mechanism behind this control [1].
First, the researchers considered the helical spin pattern that is naturally hosted by a Ni1/3NbS2 material in which nickel atoms are inserted between layers of niobium disulfide. This material is a van der Waals antiferromagnet, meaning that it is held together by weak van der Waals forces and that adjacent electron spins align in an antiparallel manner. Then, in experiments, the team found that applying an electric current to this material caused the helical pattern to rotate and adopt a different quantum state. This state was detected by measuring a change in the material’s resistance and other electronic properties.
In numerical simulations, the researchers showed that the spin current induced by the applied electric current transferred its angular momentum to the spins in the helical spin pattern, causing them to rotate collectively through an effect known as spin–orbit torque. The team says that, beyond the implications for spintronic devices, these findings improve our understanding of spin dynamics in van der Waals antiferromagnets.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- K.-X. Zhang et al., “Current-driven collective control of helical spin texture in van der Waals antiferromagnet,” Phys. Rev. Lett. 134, 176701 (2025).