Shining different laser wavelengths on magnetite can change its state, making it more or less conducive to electricity

https://phys.org/news/2024-06-electronics-ultrafast-lasers-magnetite.html

"drive magnetite into distinct non-equilibrium metastable hidden phase states (intermediate states not normally accessible) at ultrafast timescales... metal-insulator transition at around 125°K... laser excitation takes solid into phases that don't exist in equilibrium...  takes place in 3 stages over 50 ps... 400 nm,visible light caused lattice to expand, reinforcing monoclinic lattice creating stable insulator... fast, efficient memory storage, sensors"