论文标题
照片诱导的绝缘体到金属过渡和连贯的声音声子在Lacoo $ _3 $ thin Fims探索的薄膜由飞秒泵浦探针椭圆测定法
Photo-induced insulator-to-metal transition and coherent acoustic phonon propagation in LaCoO$_3$ thin films explored by femtosecond pump-probe ellipsometry
论文作者
论文摘要
我们研究了Lacoo $ _3 $和LA $ _ {0.5} $ sr $ _ {0.5} $ COO $ _3 $的超快动力学的超快动力学。我们已经观察到泵$ _3 $中的泵诱导的光谱重量转移，这与绝缘体到金属过渡相对应。光诱导的金属状态最初通过快速过程放松，衰减常数约为200 fs。 Lacoo $ _3 $和LA $ _ {0.5} $ SR $ _ {0.5} $ COO $ _3 $在1-30 PS范围内显示出重要的二级瞬态结构。对具有不同厚度的膜的测量结果表明，它对应于声学脉冲的传播。在超过100 ps的时间尺度上，进行底物的热扩散发生，可以用双指数衰减对其进行建模。
We have studied ultrafast dynamics of thin films of LaCoO$_3$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ with femtosecond pump-probe ellipsometry in the energy range of 1.6-3.4 eV. We have observed a large pump-induced transfer of spectral weight in LaCoO$_3$ that corresponds to an insulator-to-metal transition. The photo-induced metallic state initially relaxes via a fast process with a decay constant of about 200 fs. Both LaCoO$_3$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ exhibit a significant secondary transient structure in the 1-30 ps range. Results of measurements on films with different thicknesses demonstrate that it corresponds to a propagation of an acoustic strain pulse. On timescales longer than 100 ps, heat diffusion to the substrate takes place that can be modelled with a bi-exponential decay.
