Oxygen-containing ferromagnetic amorphous alloy and method of preparing the same

A method of preparing an oxygen-containing ferromagnetic amorphous alloy, said method comprising the step of:

• sputtering an oxygen-containing composite target composed of an oxide and a metal or a metal alloy, in the absence of externally supplied oxygen gas, thereby forming a film of said amorphous alloy on a substrate, said amorphous alloy consisting of:
• M.sub.x G.sub.y O.sub.z
• wherein M is one or more transition elements of Fe, Co and Ni or a combination of said transition element or elements and one or more elements selected from the group consisting of V, Cr, Mn, Nb, Mo, Hf, Ta, W, Pt, Sm, Gd, Tb, Dy and Ho;
• G is one or more elements selected from the group consisting of B, Si, Ge, As, Sb, Ti, Sn, Al and Zr;
• oxygen (O) is supplied by said oxide;
• and x, y and z are the fractional atomic percentages of M, G and O and x+y+z=100, the composition of said amorphous alloy being in the pentagonal hatched zone in the attached FIG. 1 and said pentagonal zone being defined by the lines joining the points of A (80, 19, 1), B (50, 49, 1), (36, 36, 28), D (36, 4, 60) and E (38.5, 1.5, 60) shown in said FIG. 1.