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博士教授（IFW Dresden）、Dr. ing教授一起提交的一揽子提案的一部分。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¿。本文主要研究了磁性形状记忆合金薄膜的生长形貌，包括晶构和机械应力对磁场诱导的晶体相变的影响。我们建议在我们的特高压系统中通过电子束蒸发在盐或软基板上制备薄合金薄膜，然后在原始非晶层的情况下进行退火程序以获得有织构的薄膜。在外加磁场作用下，部分独立薄膜的形状记忆相变与微观结构（晶粒尺寸、形貌、织构）、薄膜及其弹性模组的机械应力状态有关。我们对这些薄膜的磁畴结构与晶体微观结构之间的关系很感兴趣。由于孪生过程的细节是未知的，我们正在寻找合作剪切事件与位错运动的组合。为此，我们建议使用扫描探针技术，如STM， AFM和MFM来分析上述相关性。随后，我们建议使用机械光谱学（可在Göttingen上获得，频率范围从准静态到kHz（不久将在MHz）），以更详细地研究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.