Strong enhancement of the tunneling magnetoresistance by electron filtering in an Fe/MgO/Fe/GaAs(001) junction.
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 10(19)   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.
Autès
G
G
Department of Mathematics, City University, London EC1V 0HB, United Kingdom. g.autes@open.ac.uk
Mathon
J
J
Umerski
A
A