光致超快磁序相变现象展示了铁磁材料在传感、微波器件、信息存储、随机存取多状态记忆等技术领域巨大的应用潜力。深入理解光致超快磁序相变微观机制可以推动铁磁材料的应用进程。La1-xAxMnO3（A=Sr, Ca, ……）铁磁材料具有庞磁电阻效应、铁磁性与导电性强烈耦合、金属-绝缘体相变等丰富的物理特性，是探索光致超快磁序相变微观机制的理想材料。本项目拟主要采用时间分辨超快X射线衍射技术，直接探测La0.7A0.3MnO3（LAMO）的光致超快磁序相变结构动力学过程，弥补时间分辨超快光反射/透射率及超快kerr等纯光学研究中材料内部及结构信息的缺失，为深入理解晶格系统如何参与并且影响光致超快磁序相变过程提供直接判断依据。

Photoinduced ultrafast magnetic phase transition shows the enormous application potential of ferrimagnetic materials in the fields of sense, microwave devices, information storage, and multi-state random access memory and so on. Thorough understanding of the micromechanism of the ultrafast phase transition will give impetus to the application process of ferrimagnetic materials. Rich physical properties of La1-xAxMnO3 (A=Sr, Ca……), such as ferromagnetic and electrical conduction coupling, colossal magnetoresistance effect, and matel-insulator phase transition, endow them as ideal materials for revealing the micromechanism of the photoinduced magnetic phase transition. In this project, structural dynamics of the transient magnetic phase transition in La0.7A0.3MnO3 thin films will be detected directly using ultrafast X-ray diffraction. The loss of internal and structural information in time-resolved reflectivity/transmission and magneto-optic Kerr effect research on this kind of materials will be aseembled. This study will supply direct judgement basis for understanding how the lattice system participate in and impact the ultrafast magnetic phase transition.