Compact electronic devices often contain numerous functional magnetic components, presenting design challenges and physical limitations for these devices. Ultra-thin magnetic materials provide an alternative approach in the miniaturization of electronics; however, they also introduce different dynamics, which scientists have yet to fully understand.

Using two-colour X-ray ultraviolet (XUV) pulses from a free electron laser (FEL), Rösner et al. developed a way to monitor magnetization dynamics of a composite material at ultrafast timescales. “Understanding how the angular momentum is transferred from photons to spins and electrons is what drives my research, and I hope it will help design new devices that are faster, smaller, and less energy consuming,” said author Emmanuelle Jal.

The XUV two-colour pulses were tuned to the iron and nickel M-edge simultaneously, with the same absolute timing, in a Fe-Cu-Ni tri-layer system. This capability has been possible thanks to an experimental technique based on a specifically developed optical device. The ability to perform single shot time traces allowed the researchers to resolve the temporal response during the demagnetization of the Fe and Ni tri-layers.

“In Femtomagnetism, this innovative technique allows us to see that there is no delay between the dynamic onset of Ni and Fe, but that there is a delay between the onset of the electronic and spin dynamic, for both Ni and Fe,” said Jal.

This approach can help future research efforts toward a better understanding of ultrafast magnetization.

“We hope this article will bring new tools in other research areas to study multi-component ultrafast dynamics that can be non-reproducible.”

Source: “Simultaneous two-color snapshot view on ultrafast charge and spin dynamics in a Fe-Cu-Ni tri-layer,” by Benedikt Rösner, Boris Vodungbo, Valentin Chardonnet, Florian Döring, Vitaliy A. Guzenko, Marcel Hennes, Armin Kleibert, Maxime Lebugle, Jan Lüning, Nicola Mahne, Aladine Merhe, Denys Naumenko, Ivaylo P. Nikolov, Ignacio Lopez-Quintas, Emanuele Pedersoli, Primož R. Ribič, Tatiana Savchenko, Benjamin Watts, Marco Zangrando, Flavio Capotondi, Christian David, and Emmanuelle Jal, Structural Dynamics (2020). The article can be accessed at