Ab initio investigation of temperature dependent effects in magnetic shape memory Heusler alloys

SPP 1239的目标是研究适用于磁力学应用的具有磁场诱导形状变化的合金材料的材料性能和加工条件的关键问题。然而，宏观行为源于微观结构的变化，这是这里要研究的。预计这种相互依存关系的具体知识为一方面改变材料特性，另一方面控制传感器/执行器系统所需的技术制造窗口开辟了可能性。这是这个联合研究计划的目的是Forschungszentrum caesar，波恩，和MPI <s:2> r Eisenforschung, dessseldorf，在实验和理论上为各自的微观结构-性能关系的关键问题作出贡献。这将包括考虑材料的实际结构，包括缺陷、局部化学变化和原子有序效应。下面应用的实验研究是基于具有明确晶格取向的heusler型三元和四元合金薄膜的mbe生长。只有在这种条件下，才能测试相对于外部磁场方向的磁效应。此外，将用微压痕探测变形特性，并伴有局部结构表征。实验结果将与理论小组Hickel / Neugebauer进行的模拟进行比较，反之亦然，进一步的理论结果有望刺激新的特定实验。

The goal of the SPP 1239 is to investigate the key questions regarding materials properties and processing conditions of alloy materials exhibiting magnetic-field induced shape changes, suitable for magnetomechanical applications. However, the macroscopic behavior is originating from microstructural changes which are to be investigated here. It is expected that the specific knowledge of this interdependence opens up the possibility for tayloring the materials properties on one hand and on the other hand to control the technical fabrication windows necessary for sensor / actuator systems. It is the aim of this joint research proposal of the Forschungszentrum caesar, Bonn, and the MPI für Eisenforschung, Düsseldorf, to contribute experimentally and theoretically to the key questions of the respective microstructure-property relationship. This will include the consideration of the material¿s real structure including defects, local chemical variations, and atomic ordering effects. The experimental study applied for below is based on MBE-growth of Heuslertype ternary and quaternary alloy films exhibiting a well defined crystal lattice orientation. Only this condition allows for testing the magnetic effects with regard to the external magnetic field direction. Additionally, the deformation properties will be probed with microindentation, accompanied by local structural characterization. The experimental results will be compared to simulations carried out by the theoretical group Hickel / Neugebauer and, vice versa, further theoretical results are expected to stimulate new specific experiments.