Researchers achieve permanent magnetic polarity reversal in twisted quantum materials using targeted laser pulses

University of Basel and ETH Zurich researchers use laser pulses to reverse magnetic polarity in twisted materials, enabling light-written electronic circuits.

By: AXL Media

Published: Mar 4, 2026, 9:14 AM EST

Source: The information in this article was sourced from University of Basel

A new approach to magnetic switching

Ferromagnetism occurs when the spins of vast numbers of electrons align in a single direction, creating a stable collective magnetic field. Traditionally, reversing the polarity of a magnet requires heating the material above its critical temperature to disrupt this alignment, allowing the spins to rearrange as the material cools. However, researchers at the University of Basel and ETH Zurich have bypassed this thermal requirement. By using a focused laser pulse, the team demonstrated that it is possible to reorient the collective spin of an entire ferromagnetic system without raising its temperature, offering a more efficient and precise method for controlling magnetic states.

Engineering twisted atomically thin layers

The breakthrough was achieved using a specialized material composed of two atomically thin layers of molybdenum ditelluride, an organic semiconductor. These layers are stacked with a slight twist relative to one another, creating a moiré pattern that fundamentally alters electronic behavior. This "twisted" geometry allows electrons to organize into topological states—configurations that are mathematically distinct and resistant to smooth transformation. In this specific quantum environment, strong interactions between electrons cause their spins to align in parallel, producing a stable ferromagnetic state even at the microscopic scale.

Laser pulses and topological control

The research team, led by Prof. Dr. Tomasz Smoleński and Prof. Dr. Ataç Imamoğlu, discovered that a laser pulse could trigger a permanent shift in the collective orientation of these spins. Unlike previous experiments that manipulated individual electron spins, this study confirmed the simultaneous switching of an entire ferromagnet measuring only a few micrometers across. The researchers noted that the topology of the material plays a crucial role in the switching dynamics, ensuring that the change in polarity is stable. To verify the success of the flip, the team used a second, weaker laser to analyze the reflected light, which provided a clear readout of the new spin orientation.