Significant magnetoresistance enhancement due to a cotunneling process in a double tunnel junction with single discontinuous ferromagnetic layer insertion

H. Sukegawa, S. Nakamura, A. Hirohata, N. Tezuka, K. Inomata

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39 Citations (Scopus)

Abstract

We fabricate CoFe/AlOx/CoFe/AlOx/CoFe ferromagnetic double tunnel junctions and observe spindependent tunneling phenomena. A middle CoFe layer becomes discontinuous by forming CoFe particles two dimensionally, of which the average diameter is evaluated to be 2.0-4.5 nm from cross-sectional transmission electron microscopy images. Below 50 K, a Coulomb gap is observed in current-voltage curves, and both magnetoresistance ratios and resistances are found to increase significantly with decreasing temperature. This indicates that a cotunneling process is dominant within the gap, which agrees very well with theoretical prediction [Phys. Rev. Lett. 80, 1758 (1998)].

Original languageEnglish
Article number068304
JournalPhysical Review Letters
Volume94
Issue number6
DOIs
Publication statusPublished - 2005 Feb 18

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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