Project Details
Projekt
Microstructure of epitaxial films of the magnetic shape memory material Ni2MnGa
Applicant
Professor Dr. Gerhard Jakob
Subject Area
Materials Science
Term
from 2006 to 2014
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 28218001
Magnetic shape memory alloys can change their shape by application of a magnetic field, since the energy for movement of twin boundaries through the crystal is lower than the magneto crystalline anisotropy. In single crystals of Ni2MnGa huge magnetostrictive effects have been achieved. For many applications as actuators and sensors thin films of these materials will be needed. In a single crystal thin film, however, there will in general be an interaction with the underlying substrate. In this research project we want on one hand to prepare single crystalline free standing films as ideal material for thin film applications. Here we will use solvable substrates and buffer layers for a selective removal of the sacrificing layers. On the other hand we want to exploit the film substrate interaction to gain insight into basic questions concerning the magnetic field induced twin boundary motion in these materials. For ultrathin films the substrate interaction is expected to suppress the martensitic phase transition. Here a determination of the critical thickness is essential. Also we want to use substrates with uniaxial surface anisotropy in order to break the cubic symmetry and to induce an austenite-to martensite transition with a single twin direction. Magnetic and structural characterization will be done in house as well as in cooperation with partners from the SPP1239.
DFG Programme
Priority Programmes
