Experimental characterization of magneto-electric composites

本项目致力于磁电耦合复合材料的合成，以及这些系统中关键的铁电/铁磁或铁电/铁磁界面的多尺度表征。微复合材料是通过有机溶胶途径产生的粉末合成的。这就产生了具有3-0和3-3形态的陶瓷。火花等离子烧结生产纳米复合材料。在项目扩展阶段，通过脉冲激光沉积（PLD）合成具有2-2和纳米级1-3形貌的复合材料来修正这些结构。多尺度表征是通过互补技术的组合来实现的。宏观上，利用第一阶段开发的设备确定本构行为，提供综合力学本构性能，如外加电场和磁场下的应力-应变曲线。关键的磁电耦合参数揭示了使用我们的改进SQUID磁力计允许对样品施加电场。复合材料对电刺激的磁响应可以以最高的精度记录下来。介观信息是通过扫描探针技术获得的，即原子、压电和磁力显微镜（AFM、PFM和MFM）。利用直线x射线和圆x射线二色性（XLD和XMCD）在同步辐射设备上的x射线吸收测量提供了微观信息。这允许对原子长度尺度下的多铁相互作用进行分析，从而在所有相关的长度尺度上产生独特的信息。此外，材料的半导体性质将进入开尔文探针显微镜所看到的材料性质描述，这是文献中第一次讨论。这些联合实验结果为本研究单元铁性能的理论建模提供了必要的输入参数和基准。

This project is devoted to the synthesis of composites with magnetoelectric coupling and the multi-scale characterization of the crucial ferroelectric/ferromagnetic or ferroelectric/ ferrimagnetic interfaces of these systems. Micro composites are synthesized via powders generated from the organosol route. This yields ceramics with 3-0 and 3-3 morphologies. Spark-plasma-sintering produces nano composites. For the project extension phase these structures are amended by composites with 2-2 and nano scale 1-3 morphologies synthesized by means of pulsed laser deposition (PLD). Multi-scale characterization is achieved by combination of complementary techniques. Macroscopically the constitutive behavior is determined utilizing the equipment developed in the first project phase providing the comprehensive mechanical constitutive properties like stress-strain curves with applied electric and magnetic fields. The crucial magnetoelectric coupling parameters are revealed using our modified SQUID magnetometer allowing for the application of an electric field to the sample. The magnetic response of the composites to an electric stimulus can be recorded with highest precision. Mesoscopic information is gained by scanning probe techniques, namely atomic, piezoelectric, and magnetic force microscopy (AFM, PFM and MFM). X-ray absorption measurements utilizing linear and circular X-ray dichroism (XLD and XMCD) at synchrotron radiation facilities provide the microscopic information. This allows for the analysis of the multiferroic interactions down to the atomic length scale yielding unique information on all relevant length scales. Furthermore, semiconductor properties of the materials will enter the description of material properties as seen by Kelvin-probe microscopy, the first time discussed in literatur. These joint experimental results yield the essential input parameters and benchmarks for the theoretical modeling of the ferroic properties within this research unit.