Giant negative magnetoresistance of semi-insulating amorphous indium oxide films in strong magnetic fields

V. F. Gantmakher, M. V. Golubkov, J. G S Lok, A. K. Geim

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We have studied magnetoresistance in thin films of amorphous indium oxide with various degrees of oxidation, i.e., with various densities of states in the vicinity of the Fermi level. A large negative magnetoresistance is observed when the films are in the insulating state. The negative field derivative ∂R/∂H of the resistance persists up to 20T, the highest magnetic field in our experiment. The magnetoresistance is described in terms of a field-dependent gap at the Fermi level. Such a gap can arise due either to tunneling in a system of fluctuation-induced superconducting clusters or to the Cooper interaction between electrons localized in shallow minima of the random potential. In the latter case, if the depth of the minima is smaller than the Debye energy, the electrons are virtually delocalized by short-wavelength phonons.
    Original languageEnglish
    Pages (from-to)1765-1778
    Number of pages13
    JournalZhurnal Eksperimental'noi i Teoreticheskoi Fiziki
    Volume109
    Issue number5
    Publication statusPublished - 1996

    Keywords

    • hopping magnetoresistance
    • transition
    • superconductivity
    • conductivity
    • dependence
    • samples

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