Ultrafast control of antiferromagnetism in a Mott insulator by photo-doping

Ultrafast photo-doping provides a possible route to control antiferromagnetic order in Mott-Hubbard insulators out-of-equilibrium [1]. However, AFM order is notoriously challenging to probe by optical techniques [2]. Here, we demonstrate time-resolved nonlinear optical rotational anisotropy as a method to detect ultrafast transient changes of magnetic symmetry group. We leverage this technique to uncover the mechanisms by which photo-carriers suppress long range AFM order in the Mott insulator Sr₂IrO₄ and by which the AFM order is temporally restored.
[1] M. Eckstein and P. Werner, Sci. Rep. 6, 1 (2016).
[2] P. Němec, M. Fiebig, T. Kampfrath, and A. V. Kimel, Nat. Phys. 14, 229 (2018).