Initial growth structure of Ni0.30Fe0.70 films dc-biased plasma-sputter-deposited on MgO(001), MgO(110), MgO(111) and on MgO(001) covered with Fe or Permalloy

Cross-sectional and plane-view transmission electron microscopy (X- and PV- TEM) were used to investigate the initial growth phase of 5-, 10-, 20- and 40-nm-thick Ni0.30Fe0.70 films, which were prepared on MgO(001), MgO(110), MgO(111) and on MgO(001) covered with a buffer layer. The 10-nm-thick BCC-F e buffer layers and the 1.7- or 5.1-nm-thick Permalloy (FCC-Ni0.70Fe0.30) b uffer layers were pre-grown on MgO(001). All of Ni0.30Fe0.70, Fe and Permal loy films were prepared at the optimum epitaxial growth condition by de-bia sed plasma sputtering at 2.9 kV in pure Ar gas. Saturation magnetization an d coercive force of some samples were measured at r.t. using a vibration sa mple magnetometer (VSM). The Ni0.30Fe0.70 films were grown in the BCC phase with Ni-Fe(001)[110]//MgO(001)[100] up to 5 nm thickness on MgO(001) while up to 10 nm on Fe/MgO(001). With increasing thickness, the growth phase tr ansformed into the stable Invar phase, i.e. into the FCC phase with Ni-Fe(0 01)[100]//MgO(001)[100]. The Ni0.30Fe0.70 FCC phase was grown from the init ial growth stage on MgO(110), MgO(111) as well as on Pemalloy/MgO(001) subs trates. Whether or not the Ni0.30Fe0.70 film can initially grow in the BCC phase depends primarily on the lattice misfit between the crystal planes in contact. The transformation of the growth phase from BCC to FCC was also c onfirmed by the thickness dependence of magnetic properties. Finally, the s tability of initial growth structures for the present sample systems was si mulated in terms of the lattice misfit between adjoining lattice planes. (C ) 2000 Elsevier Science S.A. All rights reserved.