HYSTERESIS AND MAGNETIC AFTEREFFECT IN AMORPHOUS COZRDY FILMS - TRENDS AND VARIATIONS VERSUS DY CONTENT

The magnetization process was studied in amorphous (Co95Zr5)100-xDyx t hin films, where 4 less-than-or-equal-to x less-than-or-equal-to 26, b etween 6 and 300 K. The films exhibit a well-defined in-plane uniaxial anisotropy K(u). The temperature dependence of the coercive field H(c ) could be related to the variations of the local anisotropy K(loc), K (u) and local defects. The thermally activated magnetic relaxation was detected for T less-than-or-equal-to 40 K, and it follows with time t he law ln(M/M(s)) = at. The constant a changes rapidly with the applie d field H. The results are explained by the sharp distribution of the energy barriers. The as deduced activation volume is about the order o f the ferromagnetically correlated volume.