ELECTRICAL RESISTIVITIES OF GAMMA-PHASE FEXNI80-XCR20 ALLOYS

In this paper we present a comprehensive investigation of electrical resistivities [rho(T)] of the gamma-phase pseudobinary Fe alloy series FexNi80-xCr20 in the temperature range 0.4-300 K. These alloys exhibit exotic magnetic behavior at and near the critical composition for ferromagnetism x(c) similar or equal to 59-63. Special attention has been given to the critical region (x similar or equal to x(c)) where we find sharp changes in rho(0) (zero temperature resistivity) as well as in the temperature dependence of rho(T). These observations have been explained as arising due to the absence of long-range magnetic order and a change in effective carrier concentration at x similar or equal to x(c). For all x(less than or equal to 66) these alloys exhibit a resistivity minimum at T = T-min. T-min continuously decreases from approximately 35 K for x approximate to 12 to approximately 6 K for x approximate to 59. rho(T) for T < T-min shows a rise (rho similar to - root T) that does not depend on the magnetic state of the alloy. For T-min < T < 80 K, rho(T) away from x(c) follows a predominantly T-2 dependence arising from electron-spin-wave scattering which shows a drastic reduction for x approximate to x(c). We also compare our data with an alpha-phase Fe25Cr75 alloy.