The researchers used a laser pulse (blue) to change the polarity of a ferromagnetic state in a special material consisting of twisted tomic layers (red). Credit: Enrique Sahagún, Scixel / University of Basel, Department of Physics Researchers at the University of Basel and ETH Zurich have demonstrated a way to reverse the polarity of a specialized ferromagnet using a focused laser beam. The advance points toward a future in which light could be used to design and reconfigure electronic circuits