EFFECTS OF MAGNETIC FIELD ANNEALING ON MICROSTRUCTURES AND MAGNETIC PROPERTIES OF NANOSTRUCTURED SM-CO/CO FILMS

摘要

A magnetic field annealing is firstly used for nanostructured Sm-Co/Co films, prepared by magnetron sputtering method. The effects of magnetic field annealing on single-layer Sm-Co films are different from that on multi-layer Sm-Co/Co films. A detailed analysis of microstructures and magnetic properties is made by means of HRTEM, Auger electron spectroscopy, XRD and Physical Property Measurement System (PPMS). From magnetic properties and microstructure analysis, it was confirmed that these differences originate from the effects of magnetic field annealing on crystallization behavior of the films. The relationship between magnetic properties and microstructures explains a different demagnetization process of single-layer and multi-layer films. For the single Sm-Co layer films, magnetic-field-annealing makes the main phases change from CaCu_5 to Zn_2Th_(17) structure, resulting in a decrease of coercivity. The results show that the magnetic field annealing is useful to improve the properties of nanostructured Sm-Co(20nm)/Co(15nm) films, which ascribe to improving the pinning effectiveness in coercivity mechanism and decreasing the magnetostatic interaction of films. A very high coercivity about 0.7T was obtained from nanoscaled multi-layered SmCo/Co films