CHARACTERISATION OF HARD MAGNETIC Nd-Fe-B THIN FILMS USING SCANNING ELECTRON MICROSCOPY AND AN ELECTRON PROBE MICROANALYSER

摘要

Hard magnetic films have many potential applications in micro-systems and serve as model systems to study the physics of magnetisation reversal in these technologically important materials. The functional properties of hard magnetic materials, in particular their resistance to demagnetisation (i.e., their coercivity), depend critically on their microstructure. In this work we will report on the characterisation of the microstructure (layer thickness, grain size and orientation, chemical composition) of thick films of NdFeB made by high rate triode sputtering. Buffer and capping layers such as Ta are used to prevent interdiffusion into the substrate and oxidation from the atmosphere, respectively. Films were made by the micro- and nanomagnetism research group of the Institut Neel and characterized by cross-sectional SEM imaging coupled with energy- or wavelength-dispersive X-ray spectrometries (EDS & WDS). Boron content was determined with EPMA measurements (LDE3H), Nd and Fe with EDX and PETH or LiF crystals.