Jumps and induced anisotropy in the magnetoresistance of CuMn

Magnetoresistances, Δρ/ρo, of CuMn 4.7 % and 1.35 % have been measured in fields ranging between + and — 35 kG and in the range of liquid helium temperatures. When the remanent magnetization mr is saturated and parallel to the field H, Δρ/ρ 0 varies linearly with H for low fields and exhibits jumps. When the field is perpendicular to the initial remanence mr, Δρ/ρ0 is quadratic in H but considerably enhanced with respect to the reversible magnetoresistance for which mr ~ 0. It is found that the magnetoresistance depends only on the vector sum χH + mr of the macroscopic reversible and irreversible magnetizations.