Structural State of Mechanically Alloyed Cu–Co Compound with a Considerable Magnetoresistance Effect

Abstract

The structural state of the Cu80Co20 compound after mechanical alloying and a subsequent thermal treatment has been studied by NMR spectroscopy and X‐ray diffraction as well as measurements of magnetic and magnetoresistive properties. The analysis of the data obtained suggests the presence of ultradispersed cobalt particles in the copper matrix. A partial dissolving of cobalt in copper is likely to take place in defect regions. Such a structure is responsible for superparamagnetism of the Cu80Co20 compound at kT > 150 K and for a considerable GMR effect (12% at T = 77 K). The shifting of X‐ray peaks of the copper matrix can be related to a coherent conjugation of Cu and Co constituents.

Giant magnetoresistance of Co Ni Cu alloys produced by mechanical alloying

“…It is no doubt that the superparamagnetism could occur in these alloys. Moreover, the superparamagnetism was confirmed by NMR spectroscopy in mechanically alloyed Co-Cu alloys in the previous work [16]. It has been also observed in other alloys, such as Cu 85 Fe 15 [17], (Co 0.7 Fe 0.3 ) 20 Cu 80 [18] and Ag-Cu-Fe [19] prepared by mechanical alloying.…”