PAK 5: "Integrated Microactuator Systems Emphasizing Ni-Mn-Ga Films with a Tailored Microstructure" INTACT - Mechanical, magnetic and morphological properties of vapor desposited magnetic shape memory alloy thin films

该提案是与 S. Fähler 博士、L. Schultz 教授（IFW 德累斯顿）、Ing. Dr.-Ing 教授共同提出的提案的一部分。 H.-H。 Gatzen（汉诺威大学）和 PD 博士 M. Kohl（卡尔斯鲁厄大学）在 SPP 1239“磁性形状”中。在这里，我们重点研究磁性形状记忆合金薄膜中的生长形态（包括晶体织构和机械应力）对磁场诱导晶体相变的影响。我们建议在我们的特高压系统中在盐或软基材上通过电子束蒸发来制备合金薄膜，然后进行退火程序，以获得原始非晶层的纹理薄膜。将在外部磁场中探索部分独立式薄膜的形状记忆相变作为微观结构（晶粒尺寸、形态、纹理）、薄膜的机械应力状态及其弹性模量的函数。我们对这些薄膜中的磁畴结构和晶体微观结构之间的相关性感兴趣。由于孪生过程的细节尚不清楚，我们正在寻找协同剪切事件与位错运动的组合。为此，我们建议使用STM、AFM和MFM等扫描探针技术来分析上述相关性。后来我们建议使用机械光谱（哥廷根提供的频率范围从准静态到 kHz（不久的将来为 MHz））来更详细地研究负责形状记忆效应的特征弛豫模式。

This proposal is part of a packet proposal together with Dr. S. Fähler, Prof. Dr. L. Schultz (IFW Dresden), Prof. Dr.-Ing. H.-H. Gatzen (Uni Hannover) and PD Dr. M. Kohl (Uni Karlsruhe) within the SPP 1239 ¿Magnetic Shape¿. Here we focus on the influence of the growth morphology including crystallographic texture and the mechanical stresses in magnetic shape memory alloy films on the magnetic field induced crystallographic phase transition. We propose to prepare thin alloy films by e-beam evaporation in our UHV-system on salt or soft substrates followed by an annealing procedure to obtain textured films in case of originally amorphous layers. The shape memory phase transition of partly freestanding films will be explored in an external magnetic field as a function of the microstructure (grain size, morphology, texture), the mechanical stress state of the films and its elastic modules. We are interested in the correlation between the magnetic domain structure and the crystallographic microstructure in these films. Since the details of the twinning process are unknown, we are looking for cooperative shearing events versus a combination of dislocation movements. For this we propose to use scanning probe technology like STM, AFM and MFM to analyse the correlation mentioned above. Later on we propose to use mechanical spectroscopy, which is available in Göttingen in the frequency range from the quasi static to kHz (MHz in the near future), to study the characteristic relaxation modes responsible for the shape memory effect in more detail.