MAGNETIC-ORDERING IN AMORPHOUS BI2O3-ZNO-FE2O3 FILMS SPUTTERED AT HIGH-TEMPERATURES

The onset of a long-range magnetic order is reported in amorphous Bi2O 3-ZnO-Fe2O3 filMS sputtered at high substrate temperatures. Samples of 0.1 Bi2O3-0.4 ZnO-0.5 Fe2O3 were deposited in a mixed oxygen-argon at mosphere at substrate temperatures T(s)=450-875 K. Films are found to be x-ray amorphous for T(s) less-than-or-equal-to 675 K. For higher T( s) values, nonmagnetic crystalline phases are precipitated in the samp le. The samples are paramagnetic at room temperature for substrate tem peratures below 475 K. A spontaneous magnetic moment is observed in fi lms deposited at higher T(s). The saturation-induction 4piM at 77 K is in the range 800-3600 G and 4piM increases with increase in T(s). The Curie temperature is found to decrease with T(s). A uniaxial anisotro py character in the films is evident from ferromagnetic resonance stud ies. Thus, data on structural and magnetic parameters indicate the pos sible presence of ordered clusters in films sputtered at high temperat ures. The presence of ordered clusters need to be independently confir med with techniques such as transmission electron microscopy.