Domain structures and dynamics in Ferromagnetic shape memory materials: Theory and Experiment - Dynamic metallographic and magneto-optical polarization microscopy of MSMA systems

• Applicant: Professor Dr.-Ing. Jeffrey McCord
• Subject Area: Materials Science
• Term: from 2006 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 28320749

This project is part of a joint collaboration aiming at the understanding of the mechanisms of magnetic and structural reorientation processes in magnetic shape memory materials.The aim of the research is to obtain a deep insight into the magneto-mechanical behavior of ferromagnetic shape memory alloys (MSMA). Our main tool to investigate those samples is optical polarization microscopy, which can detect the polarization contrast of different twin variants. We will also explore the magnetic domain structure, using a magneto-optical indicator film technique. Being able to study both, the magnetic and mechanical microstructure, enables us to investigate interdependencies and mutual influences of the two different microstructures.The studies will include quasi-static processes in slowly changing magnetic fields and faster reversal using pulsed magnetic fields with temporal resolutions of the order of a few microseconds. The investigations will also incorporate studying the samples with varying temperatures in order to determine the contributing effects, which act on twin boundary motion and mobility.The results will provide useful input to the theory groups in the package to test and refine their models on the magneto-mechanics in MSMA samples.Moreover, the project extensively profits from the strong interaction with other preparational and experimental groups participating in the SPP 1239.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1239: Modification of Microstructure and Shape of Solid Materials by External Magnetic Fields
• Participating Person: Professor Dr. Rudolf Schäfer