中文摘要：

利用飞秒时间分辨光抽运探测技术研究了电子型掺杂La2-xCexCuO4（LCCO）高温超导材料的准粒子超快动力学过程．得到低温（T〈0．7Tc）、转变温度附近（0．7Tc≤T≤Tc）和高温（T〉Tc）三个温区内的动力学行为．研究发现，低温时准粒子寿命随温度上升而下降，接近转变温度时出现反常的上升，正常态准粒子寿命受赝能隙影响明显大于金属中电声子的弛豫时间．还发现电子型掺杂LCCO光感生反射率变化AR／R动力学曲线存在皮秒量级的上升过程，它反映Cooper对被打散的时间较长，上升时间随温度增加而变短．采用Rothwad和Taylar提出的理论模型对实验结果进行了分析．

英文摘要：

The quasiparticle dynamics in the electron-doped high-Tc superconductor La2- x Cex CuO4 （LCCO） was investigated by uhrafast time-resolved optical pump-probe technique. We present results in three temperature regions： namely the low temperature （T〈0.7Tc） region, that around Tc（0.7Tc≤ T≤ Tc） and the high temperature （T 〉 Tc） region. In general, there was a slowdown of the relaxation as the temperature decreases. However, the quasiparticle lifetime was found to exhibit a quasi-divergence as the temperature approached Te from below. The relaxation time in normal state was much longer than what was expected for metallic relaxation, indicating the presence of a T-independent pseudogap. We have also observed picosecond rise component of photoinduced change in reflectivity AR/R in the electron-doped LCCO, which is attributed to the Cooper pairbreaking dynamics. The rise time became shorter as the temperature increased. The experimental results are analyzed by Rothwarf-Taylor model.