稀土正铁氧体单晶及其异质结构的可控制备与超快磁光效应

项目名称： 稀土正铁氧体单晶及其异质结构的可控制备与超快磁光效应

项目编号： No.91622126

项目类型： 重大研究计划

立项/批准年度： 2017

项目学科： 一般工业技术

项目作者： 成昭华

作者单位： 中国科学院物理研究所

项目金额： 80万元

中文摘要： 稀土正铁氧体晶体RFeO3(R=稀土离子) 由于具有复杂的倾斜反铁磁结构和强的自旋-轨道-晶格耦合，表现出独特的磁光效应而成为凝聚态物理和材料领域的研究热点。尽管对稀土正铁氧体的研究始于上世纪五十年代，但近年来，超快光磁激发工作中取得的进展又激发了人们重新研究其超快磁光效应。利用磁光材料的光电磁的耦合和转换，可制成具有各种功能的新型磁光器件。到目前为止，超快RFeO3磁光效应研究仅在可见光范围，对深紫外区域的磁光效应仍是空白。同时，脉冲激光诱导的自旋进动发生在低温范围，这严重制约了其作为磁光器件的应用。本项研究拟生长正稀土铁氧体单晶RFeO3及其异质结构，阐明晶体结构、电子结构和自旋结构对超快磁光效应的影响；通过时间分辨磁光效应和磁圆二色性，发展对电子结构与自旋结构的超快、超灵敏探测的新手段，为超快磁光材料与器件的应用提供理论指导和技术途径。

中文关键词： 超快磁光效应；倾斜反铁磁结构；稀土正铁氧体单晶；界面耦合；异质结

英文摘要： Rare-earth orthoferrites RFeO3 (R=rare earth elements) exhibit unique magneto-optical effect owing to their complex magnetic structure and strong spin-orbit-lattice coupling. Although the structure and magnetic structure have been well investigated since 1950’s, recently scientists pay a lot of attention on the ultrafast optical switching and magnetic excitation, multiferroic properties of rare-earth orthoferrites RFeO3. By manipulating and transferring the light, electric and magnetic signals of magneto-optical materials, we can design novel magneto-optic devices. However, up to data, ultrafast magneto-optical properties of RFeO3 were only investigated by the laser with visible light. Meanwhile, it is difficult to trigger spin dynamics of pure RFeO3 orthoferrites single crystals by ultrafast laser heating around room temperature, which limits their application as magneto-optical device.. In the project, we will grow RFeO3 single crystals by means of floating-zone and Fe/RFeO3 heterostructures by molecular beam epitaxy techniques. We also investigate the effect of crystal structure, electronic structure and spin structure on the ultrafast magneto-optical effect by using time-resolved magneto-optical Kerr effect (TRMOKE), and deep Ultraviolet laser based magnetic circular dichroism spectrometers. We investigate room temperature ultrafast-laser-induced spin dynamics in exchange-biased Fe/RFeO3(100) (R=Er and Dy) heterostructures. In addition to the spin precession of Fe with frequency of several GHz, the quasi-ferromagnetic resonance mode, impurity mode, and unexpected coherent phonon mode of AFM in the heterostructures were triggered by ultrafast laser at room temperature. We will explain the improved efficiency of multimode spin dynamics excited by ultrafast laser is attributed to the optical modification of interfacial exchange coupling between Fe/RFeO3(100). Our work will reveal that the optical modification of interfacial exchange coupling between Fe/RFeO3(100) can open a new avenue to engineer the ultrafast spin dynamics of rare-earth orthoferrites and expand the application of ultrafast magneto-optical devices.

英文关键词： Ultrafast magneto-optical effect;Canting anti-ferromagnetic structures;Rare-earth orthoferrites single crystals;Interfial coupling;heterostructures