The initial growth structure of Ni1-xFex (x ˆ 0:6ÿ0:8) ®lms dc-biased plasma-sputter-deposited on

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 Ni1-xFex (x ˆ 0:6ÿ0:8) ®lms, prepared on MgO(0 0 1) covered with a buffer layer of Fe or Ni as well as on naked MgO(0 0 1). The 100 nm thick buffer layers of Fe and Ni were pre-grown on MgO(0 0 1). All of Ni0.20Fe0.80, Ni0.40Fe0.60, Fe and Ni ®lms could be epitaxially grown at 2508C by dc-biased plasma sputtering at 2.9 kV in pure Ar gas. The ®lms of Ni0.20Fe0.80 and Ni0.40Fe0.60 were grown in their own stable phase, bcc and fcc on MgO(0 0 1), respectively. However, Ni0.20Fe0.80 ®lm could be grown in fcc phase pseudomorphic with Ni(0 0 1) up to 20 nm thick on Ni/MgO(0 0 1), while Ni0.40Fe0.60 ®lm in bcc phase pseudomorphic with Fe(0 0 1) up to 10 nm thick on Fe/MgO(0 0 1). With increasing thickness, their growth phases transformed into their own stable phases. Whether or not the pseudomorphic phase may be induced and what its critical thickness may be should depend primarily on the lattice mis®t between the crystal planes in contact. The growth mode of Ni0.40Fe0.60 ®lm was investigated more in details to be compared with the simulations of the average strain energy versus thickness and with those of the critical thickness of the pseudomorphic ®lms versus the lattice mis®t between the contacted crystal planes. # 2001 Elsevier Science B.V. All rights reserved.