Time-resolved ultrafast EUV magnetic scattering was used to test a recent prediction of >10 km/s domain wall speeds by optically exciting a magnetic sample with a nanoscale labyrinthine domain pattern. Ultrafast distortion of the diffraction pattern was observed at markedly different timescales compared to the magnetization quenching. The diffraction pattern distortion shows a threshold-dependence with laser fluence, not seen for magnetization quenching, consistent with a picture of domain wall motion with pinning sites. Supported by simulations, we show that a speed of ≈ 66 km/s for highly curved domain walls can explain the experimental data. While our data agree with the prediction of extreme, non-equilibrium wall speeds locally, it differs from the details of the theory, suggesting that additional mechanisms are required to fully understand these effects.
@article{arxiv.2303.16131,
title = {Evidence of extreme domain wall speeds under ultrafast optical excitation},
author = {Rahul Jangid and Nanna Zhou Hagström and Meera Madhavi and Kyle Rockwell and Justin M. Shaw and Jeffrey A. Brock and Matteo Pancaldi and Dario De Angelis and Flavio Capotondi and Emanuele Pedersoli and Hans T. Nembach and Mark W. Keller and Stefano Bonetti and Eric E. Fullerton and Ezio Iacocca and Roopali Kukreja and Thomas J. Silva},
journal= {arXiv preprint arXiv:2303.16131},
year = {2023}
}