Structural and magnetic properties of CoFe alloy films

Abstract

The investigation of the structural and magnetic properties of bcc Co1−xFex (0.1<x<0.4) alloy films prepared on MgO(001) substrates using e-beam evaporation and pulsed laser ablation deposition (PLAD) methods is reported. Both structural and magnetic properties seem to be strongly correlated to the deposition conditions, i.e., substrate temperatures (Ts) and deposition rates (DR). To identify the stability limits of the bcc structure in the phase diagram, our study is limited to the Co-rich compounds. For x⩾0.3 at high Ts (500 °C), alloy films deposited by e-beam evaporation exhibit a bcc (001) growth, showing the magnetic anisotropy with easy axis parallel to the MgO [100] crystal axis. In the PLAD technique, the excellent bcc (001) film growth is observed at Ts=300 °C for x=0.25 which is close to the concentration limit of the bcc regime in the equilibrium bulk phase diagram, whereas the same compound films deposited at high Ts reveal the mixed phase of fcc (001) and bcc (001) structures. Magnetic hysteresis measurements of the film grown by the PLAD technique exhibit similar results to those of the films deposited by e-beam evaporation. These results show that, for the well-crystallized films with a bcc (001) texture, the magnetocrystalline anisotropy develops in-plane.