Structure and magnetic properties for FePt thin films prepared on MgAl₂O₄ and MgO substrates

Abstract

  In order to investigate the effect of lattice mismatch between FePt thin films and single crystal substrates on the tetragonality and the magnetization process, FePt thin films have been fabricated on MgAl₂O₄ (MAO) (100) and MgO (100) single crystalline substrates at a substrate temperature of 700 °C. The Fe concentration in the FePt films was varied from 45.0 to 50.8 at. %. In addition to the fundamental (002) peak, (001) and (003) superlattice peaks have clearly been observed in the X-ray diffraction patterns for all the samples, indicating the formation of L1₀ ordered structure. The magnetization measurements show that all the samples are perpendicularly magnetized. Large coercivity (Hc) of 57.8 kOe and 54.4 kOe was observed for the films with Fe_49.3Pt_50.7 and Fe_48.3Pt_51.7 (at. %) deposited on MgO and MAO substrates, respectively. It was confirmed that good hard magnetic properties can be obtained for the Fe₄₉Pt₅₁ (at. %) thin film.