Autès, G.; Mathon, J. and Umerski, A.
Strong enhancement of the tunneling magnetoresistance by electron filtering in an Fe/MgO/Fe/GaAs(001) junction.
Physical Review Letters, 104(21),
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Calculations of the tunneling magnetoresistance (TMR) of an epitaxial Fe/MgO/Fe tunneling junction attached to an n-type GaAs lead, under positive gate voltage, are presented. It is shown that for realistic GaAs carrier densities the TMR of this composite system can be more than 2 orders of magnitude higher than that of a conventional Fe/MgO/Fe junction. Furthermore, the high TMR is achieved with modest MgO thicknesses and is very robust to disorder at the Fe/GaAs interface and within the GaAs layer itself. The significant practical advantage of this system is that huge TMRs should be attainable for junctions with modest resistances. For a GaAs carrier density of 1019??cm-3 the system is calculated to have a TMR in excess of 10?000% but its resistance is equivalent to that of a conventional Fe/MgO/Fe junction with only 6–7 at. planes of MgO.
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