High-coercivity CoPt alloy films prepared at ultra-high Ar pressure

Large coercivity of 4.8 KOe with fine grains and smooth surface was obtaine d in Co0.27Pt0.73 alloy film deposited directly on heated glass by sputteri ng an alloy target at ultrahigh Ar pressure of 20 Pa. The effect of Ar pres sure on the microscopic structure and magnetic anisotropy was investigated. The increase of the coercivity with the sputtering pressure was attributed to the increase of the perpendicular magnetic anisotropy but not the chang e of microscopic structure. The similarity of Kerr hysteresis loops of a fi lm on and without substrate showed clearly that the perpendicular magnetic anisotropy did not result from external strain. Strong evidence is shown th at there was Go-rich phase segregation in the films with strong perpendicul ar magnetic anisotropy. (C) 1999 Elsevier Science S.A. All rights reserved.