1. Single laser pulse driven thermal limit of the quasi-two dimensional magnetic ordering in Sr$_2$IrO$_4$
- Author
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Wang, Ruitang, Sun, J., Meyers, D., Lin, J. Q., Yang, J., Li, G., Ding, H., DiChiara, Anthony D., Cao, Y., Liu, J., Dean, M. P. M., Wen, Haidan, and Liu, X.
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Upon femtosecond-laser stimulation, generally materials are expected to recover back to their thermal-equilibrium conditions, with only a few exceptions reported. Here we demonstrate that deviation from the thermal-equilibrium pathway can be induced in canonical 3D antiferromagnetically (AFM) ordered Sr$_2$IrO$_4$ by a single 100-fs-laser pulse, appearing as losing long-range magnetic correlation along one direction into a glassy condition. We further discover a `critical-threshold ordering' behavior for fluence above approximately 12 mJ/cm$^2$ which we show corresponds to the smallest thermodynamically stable $c$-axis correlation length needed to maintain long-range quasi-two-dimensional AFM order. We suggest that this behavior arises from the crystalline anisotropy of the magnetic-exchange parameters in Sr$_2$IrO$_4$, whose strengths are associated with distinctly different timescales. As a result, they play out very differently in the ultrafast recovery processes, compared with the thermal equilibrium evolution. Thus, our observations are expected to be relevant to a wide range of problems in the nonequilibrium behavior of low-dimensional magnets and other related ordering phenomena.
- Published
- 2021
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