Experimental characterization of magneto-electric composites

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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.