GIANT MAGNETORESISTANCE IN MELT-SPUN CU-MN-AL RIBBONS

Giant negative magnetoresistance (GMR) has been observed in melt-spun CuxMnyAlz (x = 50-65, y = 5-25, z = 25-30) ribbons, with a value of(R( H) - R(0))/R(0) approximate to 15% at 30 K. The GMR was found not to s aturate even in a field of 50 kOe, whereas the magnetization is satura ted at low fields. X-ray diffraction patterns showed a mixture of Cu2M nAl (2:1:1) and Cu9Al4 (9:4)phases in the Cu-rich samples and a single 2:1:1 phase in the samples with relatively higher Mn content. Microst ructure studies show a fine mixture of Cu2MnAl and Cu9Al4 phases which we believe to be the main cause of the GMR.