ACTA

Giant Magnetoresistance in Melt-Spun Co-Cu Modified by Rare Earths

B. Idzikowski^a,b, U.K. Rössler^a, A. Handstein^a, K. Nenkov^a and K.-H. Müller^a
^a Institut für Festkörper- und Werkstofforschung Dresden, P.O. Box 270016, 01171 Dresden, Germany
^b Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland

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Samples of the composition RE_xCo₂₀Cu_80-x, RE = Sm, Gd or Dy (x = 0, 1, and 3) were produced by melt-spinning and subsequent annealing. The magnetoresistance is negative as in granular Co-Cu, but its values depend on the kind of rare earth element added and on changes in the microstructure induced by thermal annealing. An addition of 1 at.% rare earth metal to Co₂₀Cu₈₀ yields a considerable increase in the magnetoresistance ratio, whereas an addition of 3 at.% causes a decrease. E.g., by addition of 1 at.% Dy to Co₂₀Cu₈₀ and optimal thermal treatment, the value of magnetoresistance ratio measured at 10 K in a field of 5 T increases from -14% to -28%. The effect can be attributed to the presence of clusters of hexagonal Dy(Co,Cu)₅, which was ascertained from X-ray diffraction data, or other, metastable rare-earth compounds and paramagnetic rare-earth atoms in the Cu matrix.

DOI: 10.12693/APhysPolA.97.791
PACS numbers: 75.70.Pa, 75.50.Tt