Effects of germanium on the electronic transport mechanism in Co₂₀ (Cu_-xGe_x)₈₀ nanogranular ribbons

Authors

J. He, Shenyang National Laboratory for Materials Science and International Center for Materials Physics
Z. D. Zhang, Shenyang National Laboratory for Materials Science and International Center for Materials Physics
J. Ping Liu, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

12-1-2002

Comments

Published in J. Mater. Res., Vol. 17, No. 12, Dec 2002. Copyright © 2002 Materials Research Society. Used by permission.

Abstract

The dependency of giant magnetoresistance (GMR) on the nonmagnetic matrix in nanogranular Co²⁰ (Cu^1-xGe^x)⁸⁰ ribbons was studied. When the matrix Cu is substituted with semiconductor Ge, the magnetoresistance transitioned from negative to positive at low temperatures. The positive GMR effect is closely related to the quantity of Co/Co³Ge²/Co junctionlike configurations. This result provides evidence for the competition between two types of electronic transport mechanisms in the magnetic granular ribbons: (i) electronic spin-dependent scattering, inducing a negative magnetoresistance and (ii) Coulomb blockade of the electronic tunneling, inducing a positive magnetoresistance.