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arXiv · 2112.08397

Decoupling of static and dynamic criticality in a driven Mott insulator

A. de la Torre·K. L. Seyler·M. Buchhold·Y. Baum·G. Zhang·N. J. Laurita·J. W. Harter·L. Zhao·I. Phinney·X. Chen·S. D. Wilson·G. Cao·R. D. Averitt·G. Refael·D. Hsieh
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Abstract

Dynamically driven interacting quantum many-body systems have the potential to exhibit properties that defy the laws of equilibrium statistical mechanics. A widely studied model is the impulsively driven antiferromagnetic Mott insulator, which is predicted to realize exotic transient phenomena including dynamical phase transitions into thermally forbidden states and highly non-thermal magnon distributions. However such far-from-equilibrium regimes, where conventional time-dependent Ginzburg-Landau descriptions fail, are experimentally challenging to prepare and to probe especially in solid state systems. Here we use a combination of time-resolved second harmonic optical polarimetry and coherent magnon spectroscopy to interrogate $n$-type photo-doping induced ultrafast magnetic order parameter dynamics in the Mott insulator Sr$_2$IrO$_4$. We uncover an unusual far-from-equilibrium critical regime in which the divergences of the magnetic correlation length and relaxation time are decoupled. This violation of conventional thermal critical behavior arises from the interplay of photo-doping and non-thermal magnon population induced demagnetization effects. Our findings, embodied in a non-equilibrium "phase diagram", provide a blueprint for engineering the out-of-equilibrium properties of quantum matter, with potential applications to terahertz spintronics technologies.

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A. de la Torre, K. L. Seyler, M. Buchhold, Y. Baum, G. Zhang, N. J. Laurita, J. W. Harter, L. Zhao, I. Phinney, X. Chen, S. D. Wilson, G. Cao, R. D. Averitt, G. Refael, D. Hsieh. 2021-12-15. Decoupling of static and dynamic criticality in a driven Mott insulator. https://doi.org/10.1038/s42005-022-00813-6

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