Design and time-resolved magneto-optical advanced characterization of Heusler compounds with large Spin-Orbit Coupling

具有大自旋轨道耦合的 Heusler 化合物的设计和时间分辨磁光高级表征

• 批准号: 237316929
• 负责人: Privatdozent Dr. Benjamin Balke
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/237316929?language=en
• 关键词: Design; time; resolved; magneto; optical

This project will focus on the interplay of exchange and spin-orbit interaction in advanced, Heusler-based materials. As the energy scale of exchange and spin-orbit interaction in magnetic materials corresponds to the sub-picosecond scale in the time-domain, time-resolved studies with femtosecond resolution are the ultimate tool in order to gain access to the interplay of those two important interactions for spin-relaxation.We will design new Heusler compounds with extremely large spin-orbit coupling, synthesize these compounds, and perform basic characterization. Advanced characterization will be performed by means of time-resolved magneto-optical methods, giving access to the ultrafast demagnetization as well as to the ultrafast magnetization switching in materials with specifically engineered spin orbit coupling as well as perpendicular anisotropy. The knowledge about spin-dependent electron dynamics acquired in such experiments can be easily transferred to interpret more general spintronics phenomena where magnetization is influenced by currents or vice-versa.The project is organized into two subprojects:a) Design of Heusler compounds with large Spin-Orbit Couplingb) Time-resolved magneto-optical characterization of Heusler compounds with large Spin-Orbit CouplingThe goal of the first subproject is the design and investigation of new compounds with extremely large spin-orbit coupling for potential applications in spintronic devices. Large spin-orbit coupling can be expected for Heusler compounds comprising high-Z elements. Especially, Heusler compounds with Sn and/or Bi on the Z-position and Pd, Pt, Ir, Ru, Rh, and Au are potential candidates. Several possible ferro- and ferrimagnetic compounds will be synthesized and investigated within the project such as X2YBi (with X= Pd, Pt, Ir, Ru, Rh, Au and with Y=TM) with cubic as well as Mn2YSn and Mn2YBi (with Y= Pd, Pt, Ir, Ru, Rh, Au) with tetragonal structure. Targets will be provided for the thin films and devices groups. In the last year of the project we will try to design a Heusler compound which is suitable for all-optical switching. This effect has been achieved up to now only in the ferrimagnetic compound GdFeCo. We will try to achieve this goal by using in the first step a Heusler compound with Gd and in the second step to exchange the Gd by Mn to end up in a rare earth free compound for all-optical switching applications.The goal of the second subproject is the advanced characterization. We will study ultrafast magnetization dynamics and the feasibility of ultrafast all-optical switching in the advanced Heusler materials optimized in subproject a). Ultrafast magnetization dynamics will be probed with the time-resolved magneto-optical Kerr effect (TR-MOKE) on specifically designed materials with fixed valence number but tunable spin-orbit coupling. This will allow pinpointing the role of spin-orbit coupling in the ultrafast demagnetization process and provide vital information about the microscopic origin of spin relaxation in advanced Heusler materials. The feasibility of alloptical switching will be tested on specifically designed ferrimagnetic Heusler compounds to verify the feasibility of this process in technologically relevant materials with high perpendicular magnetic anisotropy.

该项目将重点研究基于豪斯勒的先进材料中交换和自旋-轨道相互作用的相互作用。由于磁性材料中交换和自旋-轨道相互作用的能量尺度对应于时间域中的亚皮秒尺度，飞秒分辨率的时间分辨研究是获得这两个重要相互作用相互作用的最终工具。我们将设计具有极大自旋-轨道耦合的新的Heusler化合物，合成这些化合物，并进行基本表征。先进的表征将通过时间分辨磁光方法进行，从而获得具有特殊设计的自旋轨道耦合和垂直各向异性的材料中的超快退磁和超快磁化转换。在这类实验中获得的与自旋相关的电子动力学知识可以很容易地用来解释更一般的自旋电子学现象，即磁化强度受电流影响或反之亦然。项目分为两个子项目：a)具有大自旋轨道耦合的Heusler化合物的设计；b)具有大自旋轨道耦合的Heusler化合物的时间分辨磁光表征第一个子项目的目标是设计和研究具有极大自旋轨道耦合的新化合物，以实现在自旋电子器件中的潜在应用。对于包含高Z元素的Heusler化合物，可以预料到大的自旋-轨道耦合。特别是Z位含有锡和/或铋的Heusler化合物以及Pd、Pt、Ir、Ru、Rh和Au是潜在的候选者。本项目将合成和研究几种可能的铁磁性和亚铁磁性化合物，如具有立方结构的X2YBi(X=Pd，Pt，Ir，Ru，Rh，Au，Y=Tm)以及具有四方结构的Mn2YSn和Mn2YBi.将为薄膜和器件组提供靶材。在项目的最后一年，我们将尝试设计一种适合于全光交换的Heusler化合物。到目前为止，这种效应只在亚铁磁性化合物GdFeCo中实现。我们将尝试通过在第一步中使用Heusler与Gd的化合物，并在第二步中将Gd与Mn交换以最终得到用于全光开关应用的无稀土化合物来实现这一目标。第二个子项目的目标是高级表征。我们将研究超快磁化动力学和在a)子项目中优化的先进的Heusler材料中实现超快全光开关的可行性。超快磁化动力学将被用时间分辨磁光Kerr效应(tr-MOKE)对特定设计的具有固定价数但自旋-轨道耦合可调的材料进行探测。这将有助于准确地确定自旋-轨道耦合在超快退磁过程中的作用，并提供关于先进Heusler材料中自旋驰豫的微观起源的重要信息。全光开关的可行性将在专门设计的亚铁磁性Heusler化合物上进行测试，以验证该工艺在具有高垂直磁各向异性的技术相关材料上的可行性。