Orders of magnitude faster all-optical switching: single laser pulse flips tiny magnetic regions without need for externally applied magnetic field

https://phys.org/news/2025-09-ultrafast-magnetization-boundary-previous-optical.html

"9.4 nm thin gadolinium-cobalt film between platinum/ copper layers on top, tantalum layer below... after 27 fs duration IR pulse, magnetization boundary propagates deep into stack heating it up... only surface-near GdCo layer initially excited strongly enough to overcome switching threshold, but switching succeeds as rest of film follows due to propagating boundary... by choosing different surrounding layers and/ or altering film thickness/ composition, can control where boundary nucleates and how fast it travels"