We investigate the static and ultrafast magneto-optical response of the hexagonal chiral helimagnet Cr1/3NbS2 above and below the helimagnetic ordering temperature. The presence of a magnetic easy plane contained within the crystallographic ab-plane is confirmed, while degenerate optical pump-probe experiments reveal significant differences in the dynamic between the parent, NbS2, and Cr-intercalated compounds. Time resolved magneto-optical Kerr effect measurements show a two-step demagnetization process, where an initial, sub-ps relaxation and subsequent buildup (τ>50 ps) in the demagnetization dynamic scale similarly with increasing pump fluence. Despite theoretical evidence for partial gapping of the minority spin channel, suggestive of possible half metallicity in Cr1/3NbS2, such a long demagnetization dynamic likely results from spin lattice-relaxation as opposed to minority state blocking. However, comparison of the two-step demagnetization process in Cr1/3NbS2 with other 3d intercalated transition metal dichalcogenides reveals a behavior that is unexpected from conventional spin-lattice relaxation, and may be attributed to the complicated interaction of local moments with itinerant electrons in this material system.
@article{arxiv.2111.11465,
title = {Disentangling Electronic, Lattice and Spin Dynamics in the Chiral Helimagnet Cr1/3NbS2},
author = {N. Sirica and H. Hedayat and D. Bugini and M. R. Koehler and L. Li and D. S. Parker and D. G. Mandrus and C. Dallera and E. Carpene and N. Mannella},
journal= {arXiv preprint arXiv:2111.11465},
year = {2021}
}