We report a transition of the giant magnetoresistance (GMR) behavior in nanocrystalline Co20(Cu1-xGex)80 ribbons from negative to positive, as the semiconductor Ge substitutes for the Cu matrix. The growth of the hexagonal Co3Ge2 compound leads to a change of the physical origin of the GMR. The normal spin-dependent transport behavior in the CoCu granular system evolves into Coulomb blockade behavior of electronic tunneling in ribbons with a Co/Co3Ge 2/Co junctionlike configuration.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)