Effect of field-induced magnetic ordering on the electrical resistance of the frustrated magnet Au80Co20

Abstract Au 80 Co 20 platelets were produced by solid-state quenching followed by furnace annealing and characterized by X-ray diffraction. Magnetization and magnetoresistance (MR) were measured from 2 to 265 K. Minima of the zero-field electrical resistance R 0 ( T ) were observed at low temperatures ( T m ≈20 K) in both as-quenched and annealed samples. These minima disappear upon applying a magnetic field. At low T , a negative MR is associated to strong frustration and a very short magnetic coherence length; at higher temperatures, a positive MR is also observed.