复合稀土正铁氧体SmxR1-xFeO3晶体的生长与超快光磁性能研究

Rare-earth orthoferrites with perovskite structure have unique magnetic properties. A series of outstanding achievement about ultrafast opto-magnetism on Rare-earth orthoferrites crystals have been published at Nature, Physics Review Letter, etc. since 2004, incuding ultrafast laser-induced spin reorientation phase transition and its coherent control by a single laser pulse. However，all the exciting experiment results were obtained at low temperature. Ultrafast laser-induced spin reorientation phase transition at room temperature is expected to have high impact on the development of novel devices based on ultrafast control of magnetic state of matter. Among the orthoferrites family, SmFeO3 displays surprisingly ferroelectric and other physical properties at room temperature. In particular, they possess the spin reorientation phase transition high above room temperature, while this point in other rare-earth orthoferrites, if exist, is well below RT. Therefore, Rare-earth composite orthoferrite SmxR1-xFeO3 is the promising candidates for realizing ultrafast laser-induced spin reorientation at room temperature. Some exciting result is found in Sm0.55Tb0.45FeO3 crystal, however, the quality of crystal is an obstacle to the demands of further and deep investigation. In this project, we will systematic investigate SmxR1-xFeO3 compounds' local phase diagrams. Based on the crystallization SmxR1-xFeO3 compounds, we will select floating zone and micro-puuling down method to grow single crystal respectively. High quality SmxR1-xFeO3 crystals will be grow through optimazing growth process, meanwhile, the ultrafast opto-magnetism, nonlinear magneto-optics, etc. physical properties will also be systematic investigated. The first-principle calculation will be employed to assist the understanding the properties. The physical mechanism of laser-induced spin-reorientation phase transitions on composite orthoferrite will be comprehensively carried out. Through this project, high quality composite orthoferrite crystals are successfully grown along with demands in the ultrafast opto-magnetism investigation; the model of opto-magnetism can be developed so that we can tailor the physical properties of orthoferrite crystals through material design in the future.

2004年起，《Nature》等知名学术刊物先后报道了关于RFeO3的超快自旋重取向以及其相干控制的研究报道，这些基于稀土铁氧体单晶材料的研究成果，都是在低温下获得，室温下的自旋重取向以及超快磁相变，不仅具有重要的学术价值，同时必将加速超快光磁效应在自旋电子器件中的应用。在众多稀土正铁氧体化合物中，SmFeO3在室温依然表现出优异的物理性能，其他RFeO3的自旋重取向温度都远低于室温。 本项目基于该类材料的研究现状，开展基于SmFeO3单晶的复合稀土正铁氧体晶体的生长研究。掌握复合稀土正铁氧体材料的晶体生长和制备关键技术，并对其物理性能和微观机制有比较深入的了解，通过材料组分的设计，优化其超快光磁和非线性磁光性能，实现室温下的超快磁相变，推动稀土铁氧体材料在新型光磁器件应用开发方面的研究工作。

2004 年起，《Nature》等知名学术刊物先后报道了关于 RFeO3 的超快自旋重取向以及其相干控制的研究报道，这些基于稀土铁氧体单晶材料的研究成果，都是在低温下获得，室温下的自旋重取向以及超快磁相变，不仅具有重要的学术价值，同时必将加速超快光磁效应在自旋电子器件中的应用。在众多稀土正铁氧体化合物中，SmFeO3 在室温依然表现出优异的物理性能，其他 RFeO3 的自旋重取向温度都远低于室温。 .本项目基于该类材料的研究现状，开展基于 SmFeO3 单晶的复合稀土正铁氧体晶体的生长研究。在众多稀土离子中，Tb3+、Dy3+以具有大的有效玻尔磁子数，因而具有优异的磁光性能，成功制备了多种组成的SmxTb1-xFeO3晶体，自旋重取向温度随着稀土Sm含量x变化说明该材料中稀土成分会对其产生的有效场有很大的影响。通过材料组分的设计，优化其超快光磁和非线性磁光性能，进而调控材料的自旋重取向温度，实现室温下的超快磁相变，为通过材料设计寻找具有合适旋重取向温度的材料提供了理论指导。