GIANT MAGNETORESISTANCE IN CU-MN-AL

Giant negative magnetoresistance (GMR) has been observed in melt-spun CuxMnyAlz ribbons (x = 50-65, y = 5-25, and z = 25-30), with values up to 15% at 30 K. GMR was observed in all samples with off-stoichiometr ic composition which had a tweed structure consisting of a mixture of Mn-rich and Mn-poor Cu2MnAl-type (2:1:1) regions and/or of a fine mixt ure of magnetic 2:1:1 and nonmagnetic Cu9Al4 (9:4) phases. The highest value was obtained in samples with the 2:1:1 phase as a majority phas e. The observed GMR is attributed to interfacial scattering at these f ine structural mixtures.