Speaker
Description
Investigating ultrafast dynamics and transport phenomena at the nanoscale necessitates simultaneously achieving both femtosecond temporal and nanometer spatial resolution in the probe, which has proven to be challenging up to the present day. Using a femtosecond coherent extreme ultraviolet source via high harmonic generation, we demonstrate subwavelength imaging of magnetic domains of Co-based magnetic thin films at the Co M$_{2,3}$ edge (~60 eV, 20.8 nm), and extract local properties of magnetic domain walls with precision below 2 nm. As such, we show that domain wall widths and positions remain largely invariant during ultrafast demagnetization, which is contrary to previous propositions of ultrafast domain wall broadening and movement from diffraction-based measurements in reciprocal space. Our technique can be easily adapted to facility-scale imaging experiments at synchrotrons and X-ray free electron lasers, combining the strength of high spatiotemporal resolution, brightness, and photon energy flexibility to resolve ultrafast charge and spin dynamics in complex systems.
References:
[1] Chang et al., Nat. Mater., accepted. arxiv: 2504.17917.
[2] Zayko et al., Nat. Commun. 12, 6337 (2021)
[3] Kfir et al., Sci. Adv. 3, eaao4641 (2017)
[4] Pfau et al., Nat. Commun. 3, 1100 (2012)
[5] Jangid et al., Phys. Rev. Lett. 131, 256702 (2023)