Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095-1547, USA.
Mani L. Bhaumik Institute for Theoretical Physics, Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA.
Phys Rev Lett. 2023 May 5;130(18):186902. doi: 10.1103/PhysRevLett.130.186902.
Upon intense femtosecond photoexcitation, a many-body system can undergo a phase transition through a nonequilibrium route, but understanding these pathways remains an outstanding challenge. Here, we use time-resolved second harmonic generation to investigate a photoinduced phase transition in Ca_{3}Ru_{2}O_{7} and show that mesoscale inhomogeneity profoundly influences the transition dynamics. We observe a marked slowing down of the characteristic time τ that quantifies the transition between two structures. τ evolves nonmonotonically as a function of photoexcitation fluence, rising from below 200 fs to ∼1.4 ps, then falling again to below 200 fs. To account for the observed behavior, we perform a bootstrap percolation simulation that demonstrates how local structural interactions govern the transition kinetics. Our work highlights the importance of percolating mesoscale inhomogeneity in the dynamics of photoinduced phase transitions and provides a model that may be useful for understanding such transitions more broadly.
在高强度飞秒光激发下，多体系统可以通过非平衡途径经历相变，但理解这些途径仍然是一个悬而未决的挑战。在这里，我们使用时间分辨二次谐波产生来研究 Ca_{3}Ru_{2}O_{7}中的光致相变，并表明介观非均匀性深刻地影响了相变动力学。我们观察到量化两个结构之间相变的特征时间 τ 明显减慢。τ 作为光激发通量的函数非单调演化，从低于 200 fs 增加到约 1.4 ps，然后再次下降到低于 200 fs。为了解释观察到的行为，我们进行了自举渗流模拟，该模拟演示了局部结构相互作用如何控制相变动力学。我们的工作强调了在光致相变动力学中渗流介观非均匀性的重要性，并提供了一个可能有助于更广泛地理解此类相变的模型。
