The dynamics of electrons, spins, and phonons induced by optical femtosecond pulses has been simulated for the polaronic crystal ${\mathrm{Pr}}_{1/2}{\mathrm{Ca}}_{1/2}{\mathrm{MnO}}_3$. The model used for the simulation has been derived from first-principles calculations. The simulations reproduce the experimentally observed melting of charge and orbital order with increasing fluence. The loss of charge order in the high-fluence regime induces a transition to a ferromagnetic metal. At low fluence, the dynamics is deterministic and coherent phonons are created by the repopulation of electronic orbitals, which are strongly coupled to the phonon degrees of freedom. In contrast to the low-fluence regime, the magnetic transitions occurring at higher fluence can be attributed to a quasithermal transition of a cold-plasma-like state with hot electrons and cold phonons and spins. The findings can be rationalized in a more complete picture of the electronic structure that goes beyond the simple ionic picture of charge order.

中文翻译：

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超短光脉冲后Pr1 / 2Ca1 / 2MnO3的磁和极化子阶的演化

飞秒光学脉冲引起的电子，自旋和声子的动力学已被模拟 ${镨}_{\mathrm{1个}/2}{钙}_{\mathrm{1个}/2}{\mathrm{二氧化锰}}_3$。用于模拟的模型是从第一性原理推导出来的计算。模拟重现了实验观察到的电荷融化和轨道次序，并随着通量的增加而增加。在高通量状态中电荷序的损失引起向铁磁性金属的转变。在低通量下，动力学是确定性的，并且通过重新填充电子轨道来创建相干声子，电子轨道与声子自由度紧密相关。与低通量态相反，在高通量下发生的磁跃迁可归因于具有热电子，冷声子和自旋的冷等离子体态的准热跃迁。可以用更完整的电子结构图来合理化这些发现，而不仅仅是电荷顺序的简单离子图。