L1₀-ordering Transformation Kinetics, Magnetic Performance And Microstructure Of Fept Particle Films

FePtAg and FePt:TiNi thin films were prepared by DC-magnetic sputtering at RT in our experiments respectively, and received particle FePt films after post-annealing processing. A serious of detection methods, such as VSM, XRD and TEM were used to help us to analyze the magnetic property, ordering transformation degree, microstructure and the interaction between FePt magnetic particles of films samples; and we also studied the whole ordering transformation process of FePtAg films intensively. The influence of high pressure heat treatment to FePt:Ag films is researched too.150nm FePtAg films were deposited at room temperature, then annealed at different temperature in high vacuum annealing stove. Ag dropping can reduce the exchange-coupling interaction between FePt magnetic particles. Results show that the promotion due to Ag dropping to ordering transformation process of FePt:Ag film is very obvious at the near500℃. This promotion should be achieved by the means of accelerating the nucleation of ordered phase, because the average size of ordered domains in FePtAg films shows no significant difference compare with it in FePt films. By dividing the ordering transformation process into two part, we find that FePt:Ag films need a higher energy (Eg) about0.9eV in growth process of ordered domain than the energy in nucleation process, which should be responsible for its high ordering transformation temperature. We tried to introduce high pressure-heat treatment method into FePt:Ag films post-annealing process, and achieved a good result. High pressure treatment is very useful for refined grain and reducing the distribution of grain size.150nm FePt:TiNi films were deposited at room temperature, then annealed at different temperature in high vacuum annealing stove. Results show that controlling the content of dropped TiNi can modulate the coercivity of FePt:TiNi films to a great extent and without significant influence in ordering degree. We can see in the dark and bright field image of TEM that TiNi dropping is useful for restraining the growth of FePt grain and reducing its size distribution. FePt:TiNi films have a positive maximum about0.1, which means that FePt grains are commendably separated; and the vast majority of exchange-coupling interaction between FePt grains is cut off.