Low-Temperature Electrical and Magnetic Behavior of Dilute Alloys: Mn in Cu and Co in Cu

Abstract

Measurements are reported of the remanent magnetization in a 1.8 atom percent Mn in Cu alloy at 4.2°K and of the low-temperature resistance, magnetoresistance, and magnetization of solid solution alloys of 0.5, 1.0, and 2.0 atom percent Co in Cu. The isothermal remanence of the Cu(Mn) alloy saturates at about 3×${10}^{-2\mathrm{}}$ (μB/Mn atom) after application of a field of about 14 kilo-oersteds, and does not increase after application of pulsed fields up to 140 koe. It is equal to the saturation thermoremanence obtained after cooling in fields ≥1.5 koe. Both remanences reverse in relatively low fields of about 2 koe. The magnetoresistance and magnetization of the Cu(Co) alloys obey the relation, $\Delta \rho =-b{\sigma }^2$, found previously for Cu(Mn) alloys, with $b$ temperature-independent in contrast to that for Cu(Mn). The low-temperature resistivity of the Cu(Co) alloys increases with decreasing temperature and no maximum occurs down to 1.6°K. The magnetization of the Cu(Co) alloys shows neither remanence nor hysteresis but is nonlinear with field and with concentration. Comparison of results on these systems with existing theories delineates the areas of agreement and of disagreement.