Inverse and oscillatory magnetoresistance in Fe(001)/MgO/Cr/Fe magnetic tunnel junctions...

The effect of Cr(001) insertion layers in Fe(001)/MgO/Cr/Fe magnetic tunneling junctions (MTJs) is studied from first-principles. It is shown that with the increase of the Cr(001) layer thickness, the tunneling magnetoresistance (TMR) first decreases rapidly and then oscillates with a two-monolayer period. At some thicknesses, the oscillation leads to a sign reversal of the TMR. The oscillatory interfacial Cr moment at the Cr-MgO interface as a function of the Cr layer
thickness, which arises from the layer-anti-ferromagnetic ordering of Cr, is the cause for the oscillatory TMR.