Reduction of Ordering Temperature of FePt–Al 2 O 3 Thin Films by N 2 Addition During Sputtering

We investigate the effect of N-2 addition during sputtering on the microstructure and magnetic properties of FePt-Al2O3 thin films. The texture of FePt phase in FePt-Al2O3 thin films changes from (111) to a more random orientation by N-2 addition during sputtering. The ordering temperature of FePt phase reduces about 100 degrees C with appropriate N-2 partial pressure. A larger coercivity of 6.0 x 10(5) A/m is obtained with N-2 partial pressure about 15%. Structural analysis reveals that a small quantity of Fe3N phase forms during sputtering and the release of N atoms during the post annealing induces a large number of vacancies in the films, which benefits to the transformation of FePt phase from fcc to fcc.