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

本提案是与S博士一起提交的一揽子提案的一部分。Fähler，Prof. Dr. L. Schultz（IFW Dresden），Prof. Dr. Ing. H.- H. Gatzen（Uni汉诺威）和PD Dr. M. Kohl（Uni Karlsruhe）在SPP 1239 <$Magnetic Shape <$<$中。本文着重研究了磁性形状记忆合金薄膜的生长形貌（包括晶体织构）和机械应力对磁场诱导晶体相变的影响。我们建议在盐或软衬底上通过电子束蒸发在我们的UHV系统中制备薄合金膜，然后通过退火程序以在原始非晶层的情况下获得纹理化膜。部分独立薄膜的形状记忆相变将探索在外部磁场中的微观结构（晶粒尺寸，形态，纹理），薄膜的机械应力状态和其弹性模量的函数。我们感兴趣的是在这些薄膜的磁畴结构和晶体微结构之间的相关性。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。后来，我们建议使用机械光谱，这是在哥廷根可用的频率范围从准静态到kHz（MHz在不久的将来），研究的特征松弛模式负责的形状记忆效应更详细。

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.