By laser pump-probe time-resolved coherent magnetic X-ray diffraction imaging, we have measured the migration velocity of antiferromagnetic domain walls in the Mott insulator Sr2IrO4 at 100 K. During the laser-induced demagnetization, we observe domain walls moving at 3x10^6 m/s, significantly faster than acoustic velocities. This is understood to arise from a purely electronic spin contribution to the magnetic structure without any role for coupling to the crystal lattice.
@article{arxiv.2511.07359,
title = {Spatio-temporal migration of antiferromagnetic domain walls in Sr2IrO4},
author = {Ian Robinson and David Yang and Ross Harder and Dina Sheyfer and Longlong Wu and Jack Griffiths and Emil Bozin and Mark P. M. Dean and Jialun Liu and Hengdi Zhao and Gang Cao and Angel Rodriguez-Fernandez and Jan-Etienne Pudell and Roman Shayduk and James Wrigley and Alexey Zozulya and Rustam Rysov and Aliaksandr Leonau and Ulrike Boesenberg and Joerg Hallmann and Anders Madsen},
journal= {arXiv preprint arXiv:2511.07359},
year = {2025}
}