Magnetic anisotropy in (, .44, .55, .67, and .78) alloy film grown on and MgO(001) by molecular beam epitaxy

FexPd1−x ( x = . 30 , .44, .55, .67, and .78) films were directly grown on SrTiO3(001) and MgO(001) by molecular beam epitaxy at 500 C. The thickness of all films is 50 nm. X-ray diffraction shows epitaxial quality and face-center- tetragonal (00l), (002), and (003) peaks indicating an FePd L10 order state for films of x = . 30 , .44 and .55. X-ray diffraction only shows (002) peaks with a relatively weak intensity for the film of x = . 67 and no (00l) peak is observed, but a broad body-center-cubic Fe(002) is identified for the film of x = . 78 . Magnetic hysteresis curves are carried out by a vibrating sample magnetometer (VSM) with an applied field within 12 kOe. Magnetization of both in-plane and perpendicular-to- the-plane measurements show a linear increase of the magnetization saturation from 560 emu/cm3 to 1250 emu/cm3 as x increasing from .30 to .78. For the results of the in-plane measurements, remanence (Mr), however, shows a minimum while the anisotropy field (Hk) shows a maximum for the film with x = . 44 indicating the optimal content ratio of Fe/Pd for perpendicular anisotropy in the present alloy films. Further, negative remanence is observed in the hysteresis curves where the field is perpendicular to the film of x = . 78 This may indicate that the L10order state still affects the magnetic anisotropy for high Fe content films even though the film has a body-center-cubic structure.