Spintronic devices enable data processing with significantly lower energy consumption. They are based on the interaction between ferromagnetic and antiferromagnetic layers. Now, a team from Freie Universität Berlin, HZB and Uppsala University has succeeded in tracking—separately for each layer—how the magnetic order changes after a short laser pulse has excited the system. The researchers were also able to identify the main cause of the loss of antiferromagnetic order in the oxide layer: The excitation is transported from the hot electrons in the ferromagnetic metal to the spins in the antiferromagnet. The findings are published in the journal Physical Review Letters.